ZGPAX S5 Chinese Watch Phone Review

The short lowdown on the ZGPAX S5: it is a full-blown Android smartphone with quite a bit of CPU power packed inside a watch form factor. Although usable as a mere ‘smartwatch’ when jumping through some hoops, it is intended as a standalone device and can be quite successful at that, when taking the time to configure it and work around the most obvious flaws.

However, some important issues lead me to not recommend this watch phone to the general public that wants to buy something that ‘just works’ out-of-the-box. Amongst these issues are poor battery life, lack of quality assurance that might result in random defects on the particular unit you will receive from the reseller, as well as some fundamental flaws in the touch screen and radio subsystems. For people with more patience and the willingness to do some hacking however, it is well worth its reasonable price tag and a good sign that wearable tech could have a bright future.

A few months after doing this review, I tested the similar IKWear IK8 which proved to be a much better designed product with very similar hardware, so you may also want to check out my review of it. I no longer use the S5, my main watch phone is now the Abardeen F80 which I obviously also reviewed.

Intro

Recently I wrote a lengthy article about smartwatches and smartphones. For clarity, I consider a ‘smartwatch’ the kind of device that only serves as a companion device to a nearby smartphone. What I call a ‘watch phone’ on the other hand, is a fully autonomous device. The article explains why I believe the concept of a device that is only useful when tethered to a nearby phone, is flawed. For me it would be a step back, because I have been using true watch phones since mid-2008.

My last watch phone, the MQ668, proved to be of poor build quality and started showing worrisome cracks everywhere, so I decided to replace it. I was also pretty frustrated by all its bugs in both hardware and software, which I had managed to fix only partially. Last but not least, I was also getting tired of its ancient operating system, limiting functionality to that of cell phones from the first years of this millennium. A strict requirement for my new watch phone was therefore that it must run Android.

Considering the available Android-based watch phones (i.e. devices that can make calls and access the internet autonomously), the offerings are still quite limited at this time. There is the Z1, which is bulky and runs an old Android release. There is the Neptune Pine, which is great feature-wise (especially because it is detachable), but it is way too large for being a watch, and at the time of this writing, still not shipped to customers. The remaining models are all very similar in form factor and specifications: one of them is the Omate TrueSmart, which has been plagued by a few disappointing setbacks like lack of Play store support, and some other issues that left a sour taste with the backers of its Kickstarter campaign. Another one is the Pearl Simvalley AW-414.go, similar to the Omate.

The Chinese have also been busy of course, and have released watch phones very similar to the Omate and AW-414.go. As usual, their pricing is pretty competitive, but if you have read my long watch phone rant, you know why. Still, one particular model caught my eye for various reasons, and in the end I decided to have a go at it. The model is the ZGPAX S5. Having learnt from my experiences with the TW810 (see MQ668 review), I ordered directly from a Chinese reseller. I asked not to try anything fancy with customs declarations, and just provide correct forms. In the end I paid a total of about €150, of which a good 30% were customs taxes, but I received the gadget quickly and without hassle.

Specifications and features

Contrary to your average smartwatch, the ZGPAX S5 is a full-fledged smartphone in a very tiny form factor. It has:

• MT6577 dual core Cortex A9 1GHz CPU, with PowerVR SG531 GPU
• 512MiB RAM
• 240x240 pixel 1.54" capacitive touch-screen
• Standard SIM card slot
• 4 GiB on-board storage
• MicroSD card slot (up to 32GiB although 64GiB might also work)
• 2 MPixel camera
• MicroUSB port
• Two hardware buttons: ‘power’ and ‘back’
• 3-axis accelerometer
• 500 mAh battery (700 mAh batteries are available).
• BlueTooth, WiFi, GPS, and FM radio.

The dimensions are almost identical to the MQ668: about 60×40×14mm, making it very wearable under clothing.

The S5 runs Android 4.0.4 with Play store access. It comes with a custom launcher that is tied together with a clock screensaver. Whenever the display turns off, the phone will show the clock face when woken up again.

In the box, next to the phone there is a microUSB cable and USB mains charger, a headset that plugs into the microUSB port, and a short instruction manual. The FM radio only works with the headset, because it needs it as an antenna.

There are no volume buttons, most apps with audio (including the phone) offer an on-screen volume control when holding down the ‘back’ key. Custom apps like Pie Control can also be used to invoke a volume control.

It is hard to stress how much of an improvement this is over the previous generation of Chinese watch phones. If I would have to give a multiplication factor of how much more useful an Android-based device like this is, compared to the average MT6225-based phone with its primitive Mediatek Nucleus operating system, I would say the factor is 1000, give or take. The mere fact that any Android app compatible with the tiny screen resolution can be installed and that I could write my own apps, makes this watch phone almost infinitely more useful.

Partially disassembled. Mind that the GSM antenna is normally connected to the tiny wire sticking out at the left. To detach the SIM and microSD slot from the main board, carefully lift up the little connector at the end of the flatcable and take care not to damage it.

What I like about the ZGPAX S5

1. It looks pretty good. It has a kind of retro-70's style to it, and unlike many of my previous watch phones it elicits spontaneous positive remarks from people.
2. The size is OK. With the 700mAh battery installed, it is at the upper limit of what I consider small enough to wear on a daily basis.
3. Standard microUSB instead of some proprietary plug, and no external cradles or adaptors necessary to charge the phone or connect it to a PC, just any standard µUSB cable.
4. Play Store access, and a large fraction of all apps just work, despite the fact that the 240×240 resolution is below the minimum requirements for the App store at this moment. There are workarounds to get less cooperative apps to work (see hacking section).
5. It is quite usable as a watch, because it will always switch back to the clock face whenever the screen wakes, and the Android interface always shows the time in the toolbar except for a few full-screen apps. The watch faces have a second hand and date indicators. Of course, the fact that a button needs to be pressed to show the time is annoying for a watch, especially because it can take up to three seconds for the screen to wake.
6. It is pretty lightweight, out-of-the-box it weighs 63 grams.
7. Overall build quality looks pretty decent. The screen seems somewhat loose, though, and there are reports of it detaching due to poor glue quality.
8. Atypical for a ‘budget’ Chinese product, there seems to be an actual company behind it with an actual website and actual contact persons. (Note from the end of 2020: website used to be at en.zgpax.com, seems dead now.) No service or software upgrades page to speak of, though. Plus, people on forums have reported slow or absent response to inquiries. It took a good week until I got a concise reply to a question about the 700mAh batteries.
9. The capacitive touch screen is very responsive (although it has a problem, see below). This compensates for the lack of ability to use any pointy object as a stylus.
10. The CPU is pretty insanely powerful for such a tiny device, and the user interface is very smooth overall.
11. The camera is of pretty good quality, although its use is limited due to the fact that it is forward-facing. It can record decent 720p video albeit with heavily compressed audio.
12. WiFi signal reception is very good, better than on some of my other devices like my larger smartphone.
13. All the electronics are contained within the main body. There are no microphones, antennas, speakers, etc. embedded in the strap, which would risk making the construction more fragile.
14. After performing the necessary tweaks and installing the right apps, the device is more practical than one might guess from its looks. I can check the weather or traffic information in about 20 seconds without having to dig for phones in my pockets.
15. There is a sizeable community, for instance on the XDA forums and Joe's Tech Review, that shares experiences, tweaks and hacks for this model.
16. Performing firmware-level hacks does not require soldering custom cables or disassembling the phone and poking the PCB with needles. Everything can be done through the standard microUSB cable. Performing software hacks is as easy (or hard, depending on skill level) as with any Android-based phone.
17. It comes with a manual in decent English, and the manual is specifically written for this model and is actually somewhat useful. It is the first time I have seen the word swastika in a manual, though.

What bothers me about the ZGPAX S5

Issues that I managed to solve through a hack or tweak are marked with a [Hacked] or [Tweaked] link to their corresponding fix in the hacks section.

1. Not detachable from the strap, and due to the tang buckle, taking the watch off the wrist when receiving a call is not practical. See the paragraph about detachability in my watch phone rant article if you don't get what I am talking about here. [Hacked]
2. Not water-resistant. If it starts raining, I am pretty much obliged to take it off and tuck it away safely, because there seem to be plenty of gaps for water to seep in.
3. When using it as a phone, it suffers from exactly the same sound quality issue as I have experienced with the TW810 and MQ668: whenever the cell signal is weak, the other party will hear a terrible buzzing instead of my voice. This is because the GSM antenna swamps the microphone circuit with radio interference. If any of you Chinese electronics engineers read this: please stop routing microphone wires near the GSM antenna, and especially do not route them parallel to the antenna. [Hacked!]
4. The accelerometers do not work on my unit, which is obviously a defect caused by the typical Chinese lack of quality control. People on online forums report other random component failures. While a Western company would reject any unit with such manufacturing defect, the Chinese seem to sell them anyway. I wouldn't mind such ‘outlet units’ being sold, if they would be explicitly labeled as such. I am certainly willing to pay a little extra for a unit that has undergone proper QA.
5. Connectivity is unstable, especially when leaving all subsystems enabled. Both the WiFi and cell data connections will lock up when left active for a long time, especially when enabling them both. WiFi also often locks up when walking around past different access points, the remedy is a toggle. Sometimes the phone will refuse to load a particular website until it has been rebooted. Overall, it is best to leave all subsystems disabled until the moment you really need them. This also improves battery life.
6. 
   The touch screen sensor has a kind of ‘dead zone’ at its bottom. The photo shows what happens when tapping the screen everywhere in the ‘handwriting’ debug mode, which should result in a uniform field of dots. Touches in the dead zone end up at the bottom, which makes hitting for instance the snapshot button in the camera app very difficult. Many people report this, so it is not just a fluke on my unit. It might be a design flaw (maybe some conductive part too close to the sensors?) It is not entirely impossible to hit coordinates in this zone though: when using my entire thumb to enlarge the contact surface, I can overcome the apparent ‘repulsive force’ that surrounds the zone.
7. Another problem with the capacitive touch sensor is that it will go completely crazy when there is just a tiny amount of water on it. By all means do not forget to turn off the screen if your sleeves are wet from rain, or your phone will launch random apps and call random people all by itself. I am very inclined to say that a resistive touch screen makes more sense on a device like this, otherwise water-resistance would only serve to prevent damage but the phone would still be unusable in wet conditions.
8. The screen supports multi-touch, but only barely. For it to work optimally, one needs to do the inverse as for the dead zone: minimise the contact area per finger. Also, do not bring your fingers too close together or they will be detected as one single blob.
9. The battery only lasts one day on light usage. Ordering a 700mAh upgrade battery is highly recommended for anyone who wants to do more than check the time and a few webpages every day. Unlike typical smartphones, the screen is not a major power hog thanks to its tiny size. Especially the WiFi and cell radios seem to be rather inefficient, and there seem to be issues with the CPU getting stuck in a high-power mode. [Tweaked]
10. The battery level display is unreliable. It tends to stay in the 90% range for a long time and then suddenly plummet. It always zips quickly through the 80%-20% range and when it passes 50%, it is already way beyond half the total time. I suspect this may be intentionally misconfigured such that it initially seems as if the battery drains slower than it does. I have looked if it would be possible to do a similar fix as I did with the MQ668, but I still haven't figured out how Android computes the battery level and how it could be corrupted.
11. Swapping batteries is cumbersome, it is nearly impossible to pry open the battery cover without the help of a screwdriver, key, or other similarly shaped object.
12. The front-facing camera is extremely unpractical for general photography. In my opinion, a front-facing camera should only be a secondary supplement to a main camera, mounted at the side of the watch body, such that one can see on the screen what is being photographed.
13. Cell phone signal reception is rather poor. As with all watch phones, your arm will absorb part of the signal when the phone is worn. This also speaks for taking the phone off your wrist while calling. Even when taking it off though, the signal seems below average.
14. The automatic switching to the watch screensaver is useful, but also annoying due to the need to go through the launcher again to get back to your running app. Ideally, I would like the phone to only switch to the watch face when the screen has been off for more than say five minutes, but there is no option whatsoever to configure anything like this. [Hacked]
15. Some of the clock faces are poorly designed. It is difficult to discern the hour and minute hands, the date text is too small, and one of the clock faces looks like it barely survived an explosion. [Hacked]
16. The 2×2 grid of the stock launcher is conservatively large, a 3×3 grid would not be less practical and would fit many more apps on a single screen. [Hacked]
17. GPS suffers from the same problems as any other smartphone based on this Mediatek chipset: one needs to jump through quite a few hoops to get it to work more or less reliably. [Tweaked]
18. GPS performance is worse when wearing the phone on the wrist, which makes sense because the wrist absorbs some of the GPS signal, just as it does with the cell phone signal.
19. It is impossible to use bluetooth keyboards or mice. They can be paired, but the phone will not respond to key presses. This is a pity because especially a mini external keyboard could be tremendously useful for texting etc. This seems to be a fundamental problem with the BlueTooth stack on this particular combination of Android version and Mediatek hardware, because I have a smartphone with almost identical specifications that exhibits the same problem.
20. The screen cannot be locked with a password nor pattern, except after rooting the phone and installing a custom launcher. On the other hand, the need for locking is somewhat moot on a device that is almost always worn, and could be more bothersome than useful. If locking would be added, it must be easy to toggle.
21. 
    Accessing ‘menu’ functionality needs to be done through a tiny and difficult to hit icon in the toolbar, due to lack of a hardware button. Luckily modern apps incorporate menu functionality in their main interface, and an app like Pie Control (see photo) can offer a much easier to reach menu button. I consider Pie Control a must-have for a device like this.
22. It has locked up a few times, the only remedy in such case is to remove the battery (which is cumbersome, see above). People on XDA forums suspect that some of the instability might be due to old data on the SIM card, so it is best to wipe old SMS messages etc. before moving your SIM from your old phone to the S5. I also suspect poor electrical contact with the SIM card to be responsible for a few lock-ups, so I cleaned the contacts and the card with contact cleaner. Not sure which of the fixes really worked, but the lock-ups are almost gone now.
23. Removing the microSD card is nearly impossible without some sharp tool.
24. Not readily usable as a smartwatch that acts as a companion device to a smartphone. I do not really care about this, but I know there are quite a few people who do. It is possible to get smartwatch functionality through installing the right apps. I refer to the XDA forums for more details.

Tweaks and Hacks

In this section I summarise the tweaks and hacks I did to tailor my S5 to my needs. Like I said before, the good thing about the S5 is that there is a community around it that shares their experiences, see for instance the XDA forums and Joe's Tech Review.

The S5 comes with what appears to be a screen protector, but it barely sticks. I recommend using pre-made protectors for the iPod Nano 6th generation, which are a perfect fit. As an alternative, any larger protector can be cut to a size of about 36×36 mm.

Engineer mode can be activated by dialling *#*#3646633#*#*, or through an app like MobileUncle MTK Tools. Only use this if you know what you are doing!

For what it's worth, digging through the system files reveals that the ZGPAX S5 uses a MMA7660 accelerometer, and the touch display controller is an FT5206.

Making it usable as a telephone

As with the MQ668, I made the S5 more practical as a telephone by fitting a 24mm deployment clasp instead of the tang buckle. This allows to take the watch off the wrist in just a few seconds, instead of either being forced to answer calls by talking to your wrist, or having the other party wait until you have fumbled open the tang buckle.

The other big obstacle for the S5 to be a practical telephone is the buzzing sound on outgoing audio. Both the cause and the fix are the same as with the MQ668: the microphone is too close to the GSM antenna. When the cell signal is weak, the antenna will transmit at maximum power and cause audible interference on the microphone signal. The microphone wires are wrapped inside electrostatic shielding, but this is insufficient. I tried to add more shielding, but it had no effect. The fact that the wires run parallel to the antenna seems to be the main problem. I tried a few configurations, but eventually I had to ensure that the mic wires went away from the antenna as quickly as possible, at a 90° angle. Just as with the MQ668, I relocated the microphone to the other side where there happened to be just enough room, and I drilled an air hole. I had to use 0.2 mm enamel wiring because anything else was too thick to route under the shielding, without affecting the tight fit of the battery. The main concern I had, was that the mic is now placed even closer to the loudspeaker than it already was, and there could be risk of feedback. There is indeed a short whistling sound at the start of a call, but it goes away immediately. Therefore the fix works perfectly, but it is obviously not something the average consumer would dare to attempt.

Do not bend the tiny flatcable to the SIM card board as I did here (I actually damaged it this way). It can be easily detached by lifting the connector up.

Battery life

The short battery life can be mitigated in two ways. The first obvious one is to buy a larger battery: 700mAh batteries are available. They are 2mm thicker than the standard battery, meaning the total thickness of the phone becomes 16mm which is still OK. Dubious new airline regulations state that LiPo batteries may only be shipped inside their original product, so it is best to order extra batteries together with the S5 itself. Chinese resellers know the problem however, as well as creative ways to work around it (I won't go into details, but they managed to ship me some batteries while neither lying nor specifying on the envelope that it contained batteries).

The second remedy for battery life is also pretty obvious: avoid consuming much energy. Do not run power-hungry apps and disable useless animations where possible. A big power hog is WiFi: only enable it when you need it (there are some apps that can do this for you), this also helps to prevent it from locking up. Likewise, if you are not using the S5 as a phone that needs to be online all the time, enable airplane mode unless you need a data connection. This can easily double the battery life. The display does not consume enormous amounts of power thanks to its small size, yet it is recommended to set it to the lowest brightness and shortest timeout you are comfortable with.

The CPU in the S5 seems prone to getting stuck in a high-power mode, causing the phone to heat up for no apparent reason even when idle (and obviously consuming a lot of power). People on the XDA forums recommend setting the CPU governor to ‘ondemand’ instead of the default ‘hybrid’ to avoid this. I recommend the following approach: first, use an app like No-Frills CPU Control to set the default governor to 250MHz/500MHz ondemand, or even 250MHz powersave if you dare. Also set the I/O scheduler to deadline. Next, use Per-App Modes to fine-tune CPU performance for specific apps. I have made a list of the profiles and app assignments that I use.

Rooting and making a backup

To install apps that can manipulate the CPU governor, as well as for pretty much every other hack I report here, the phone must be rooted. Framaroot is reported to work, but it did not work on my S5. I used Cydia Impactor instead.

Once the phone has been rooted, the next step is to create a Nandroid backup so you can restore it in case you have badly messed up. I recommend Rashr (used to be on Play store as de.mkrtchyan.recoverytools) to install either TWRP or CWM. Follow the instructions from the ‘Recovery’ section on the XDA forum post. I made a tweaked version of the TWRP ui.zip interface file [Download]. Drop it in /sdcard/TWRP/theme/. You may still need a magnifying glass to see what you're doing, but the interface elements are better arranged.

Keyboard

Forget about typing text with the standard keyboard, or the custom ‘iFlytek’ keyboard that is preinstalled: the keys are unpractically small. I recommend installing Slidy Press, which is a half-size keyboard with much larger keys. The most common letters are typed by tapping the keys, while the less common secondary keys are accessed by sliding over the keys. To avoid a bug with the backspace key, always slide left on the ‘u’ key to type a ‘p’.
If you find the Slidy Press keyboard difficult to read, I have made a tweaked version with a big bold font: [Download, currently based on 1.3 version]. Uninstall the Play store version before installing this APK manually. Disclaimer: I give no warranties for this modified app whatsoever and it must not be redistributed.

The Qwerty5 keyboard extends on the concept of Slidy Press by squeezing three keys into one, which makes it more compact. Unfortunately it cannot be installed from within the Play Store: you need to obtain the APK in another way (e.g. install it on another phone) and sideload it. Another alternative that is reported to work well is the Swype keyboard. All these alternative keyboards take some time getting used to, but are certainly worth it.

Better launcher and clocks

I kind of like the simplicity of the stock launcher, so instead of installing a custom one, I hacked it to better fit my needs. You can download this customised launcher here. To install, use a root explorer app to overwrite the existing /system/app/SzkctLauncher.app (obviously, make a backup of the original). Ensure permissions and owner are set correctly (rw-r--r--, root:root), and reboot. Only do this if you have a backup and know how to unbrick your phone. I give no warranties whatsoever! These are the included fixes:

1. Disable the automatic switch-back to the clock screensaver altogether. I would have preferred to implement a timeout, but this is too difficult to achieve through editing smali code. To see the clock, now I need to go back to the launcher and press the return button. This is OK, especially in combination with Pie Control which mimics a ‘Home’ button.
2. Change the app grid from 2×2 to 3×3. I also spiced up the layout a bit.
3. Tweak the clock faces. Mind that there are two flavours of the launcher: the older one only offers three rather ugly clock faces with no second hand, the newer has five better-looking faces with second hand. My hacks are based on the new one. I improved overall readability of the clock faces and redesigned the second face.

Adjusting app resolution

Some apps are unusable because parts fall outside the small screen (one example is the settings menu in Per-App Modes). To work around this, install the XPosed framework as explained in the XDA forums. Next, install the App Settings plugin (a few reboots are required to activate everything). In App Settings, create a profile for the problematic apps. To fit more stuff on the screen, set the DPI to a value lower than the default for the ZGPAX S5, which is 120 DPI. Likewise, you can enlarge the interface by using a DPI above 120. You can also tweak the font size to compensate for the rescaled interface.

A few examples: for Per-App Modes I recommend a DPI of 100 with a font scale of 110. For the Camera app, set DPI to 125 and font scale to 96: this moves the snapshot button down, making it much easier to hit.

GPS tweaks

To get the most out of the notoriously fickle Mediatek GPS that plagues all phones with this chipset, you should first of all install an app like FasterGPS and select an NTP server as close to your location as possible. Next, you need to enable some options of the GPS system that are disabled by default. You can do this in System Settings, but I recommend using Engineer mode when doing it for the first time. Go to ‘LocationBasedService’ and enable A-GPS, and EPO. You could try using the auto-download EPO feature, but it almost never works as of lately because the server that hosts the file can no longer handle the load. You should use an app that updates the file instead. My own EPO Updater is very simple, lightweight, and is especially suitable for the small screen of the S5. It should suffice to do all this once, except the EPO update should be performed once every month.

I recommend installing the app ‘GPS Status & Toolbox’, and running it whenever you plan to use the GPS, such that it can update your A-GPS data and ‘warm up’ the GPS. Configure the app to keep the screen awake. Under clear skies, the GPS should get a fix (satellites marked in green) within less than two minutes. Taking the phone off your wrist seems to help to speed up obtaining a GPS fix. Sometimes the S5 may end up in a state where it fails to obtain a fix no matter what. If this happens, try deleting the /data/misc/mtkgps.dat file and rebooting the phone to reset its state.

Mind that the GPS is inherently bug-ridden on all phones with this chipset. It is quite typical for the GPS to get in a messed-up state after it has lost its satellite fix due to e.g. driving under a bridge. The only remedy in such case is turning the GPS off and on again, after which it will typically regain its fix within seconds.

Other small fixes

The preinstalled Google Calendar cannot sync with online accounts because GoogleCalendarSyncAdapter.apk is missing. You can either get the right version of that APK (look for “YourZgapps XS 4.0.4”), drop it in /system/app/ and install it from there, or disable the preinstalled app and install the Calendar app from the Play store.

The microUSB port is not protected, but little rubber plugs are available that can be inserted to keep dust from getting inside.

Conclusion

This is definitely the best watch phone I have had so far (until I got the IKWear IK8), but it still is not quite ‘there’. The overall impression is that of a typical Chinese product, hastily brought to market before being properly tested and finished. The good thing about it, is that it runs Android and is therefore much easier to tweak than the closed platform of the older watch phones. However, it has some hardware defects that cannot be fixed in software.

In my opinion, the following problems need to be fixed before a device like this could have any success with the general public:

1. Detachability. I have ranted enough about this before, so read the article if you want to know more. Even for people who only want to use it as a smartwatch and never make calls, it can still be practical to quickly take the phone off the wrist, e.g. to take photos or charge it.
2. The various connectivity issues with the GSM connection, WiFi, Bluetooth, and the buzzing noise when making calls, must be eliminated. Cell phone signal reception should be better.
3. Battery life: having to charge a wristwatch every day is cumbersome! I know this is by far the biggest challenge, but there must be solutions for it. For starters, the S5 could probably last twice or thrice as long on the same charge if the cell radio had been more efficient and the OS were better optimised.
4. The touch screen must work perfectly. I am still inclined to say that a device like this would be better off with a resistive touch screen, which also enables the use of a stylus.
5. Better quality control! I'd gladly pay a little more for a product of which all parts are guaranteed to work.
6. Better preinstalled software, for instance a keyboard like Slidy Press that is tailored to tiny screens. Something similar to Pie Control, even if only a very basic version of it, would also greatly enhance the experience. The clock screensaver must be configurable such that it only activates after a certain period of inactivity. There must be a way to lock the phone as well.
7. GPS must work out-of-the-box, not only after doing the typical MTK dance of manually enabling EPO, A-GPS, etc.
8. The screen should make use of the entire top surface of the device, without any bezels. This would offer 60% more usable area without making the phone any larger.
9. A light sensor to adjust the screen brightness automatically.
10. Continuous time display: obviously also very difficult to implement, especially together with longer battery life.

The bottom line is that I would not recommend the ZGPAX S5 to anyone except the hardcore watch phone enthusiast. The IKWear IK8 is a much better choice if you want similar hardware for a similar price, in a better designed end-product. Last but not least, the Abardeen F80 is detachable, has twice the amount of RAM and a much better touchscreen, and runs a more recent Android version. The Omate TrueSmart and Pearl/SimValley watch phones might score a little better on the quality front, but they also suffer from awful battery life and the general lack of Android support for such tiny screens. The Pine looks promising but is way too large as a watch. Nevertheless, they all give me good hopes that we are coming closer to a truly usable watch phone.

Many thanks to the people over at XDA forums and Joe's Tech Review (defunct, used to be at joestechreview.ning.com) for inspiration for the hacks and tweaks, and for giving me the idea to buy the S5 in the first place!