Let's have a look at the hardware first and we find that, unusually, this XDA is not made by HTC. What we have is a customised version of the Asus GM5, in black with a polished metal strip around the bottom and lower third of the sides. The front sports a (beautifully tactile) five-way navigator in a matching shade of silver plastic with call/end and Windows/OK buttons arranged around it. These are below the 2.8" screen, whilst above it we find the VGA camera for video calling, an LED and the phone speaker. The glossy plastic and touchscreen suggest the Zest would be a fingerprint magnet, but actually its not bad at all in this respect.
The left hand side has the volume keys and a connector for an external GPS antenna. On the right we find a button for the camera and the lock slider. On the bottom are the mini USB power/headset connector, a microphone and a lanyard loop. The one-piece back covers the 1300mAh battery, SIM and Micro SD card slot. There are also cut outs for the speaker and 3 Mpixel camera, although this lacks an LED light for low light pictures. In the top right corner sits the one piece plastic stylus which will never, ever fall out of its silo such is the tightness of the fit. A spare is included in the box should you ever leave it behind though. Lastly, on top there is a power switch which turns the device on and off rather than enabling standby as on some other phones. That is a function of the lock slider on the right hand side.
The lock slider is worthy of seperate mention proving to be a far more natural way of putting the Zest to sleep and locking than any of the button types that you'll find elsewhere. If the Zest has no other impact on the smartphone market it will certainly change this particular part of the user interface, its that good.
Inside you'll find Wifi, Bluetooth, HSDPA 3G and a-GPS (using the SIRF-III chipset). The full range of Bluetooth profiles is supported, including A2DP for sending music to stereo headphones.
The specs of the Zest make for impressive reading, a 624 MHz Marvell processor keeps things humming along at a good pace, whilst that 2.8" screen sports a 480 x 640 VGA resolution, giving it an amazing sharpness and clarity and allowing text to be readable even at unfeasibly small sizes. Of the 128 MB of RAM approximately 55 MB are free after a soft reset, leaving plenty for multiple programs to run without having to worry about closing them down to free space.
Weight is a very light 118g and the overall size is incredibly small - about the same as the original HTC Touch. In the hand the Zest is perfectly sized - even remaining comfortable through long sessions of text entry using Transcriber hand writing recognition. Its also comfortable to use for long periods of calling, which is good, because the call quality and excellent signal will prompt you to make extensive use of the Zest as a phone. Even the speaker phone works well.
Moving to the software side of things we have version 6.1 of Windows Mobile. I have to say how impressed I am with the stability of this build. 6.0 was good in this respect, but the Zest has had the stability of an old-style Novell server - it has run without a single reset or program crash since first switch on and, to be honest, it feels like it will keep doing so for as long as I keep using it. In my experience Windows Mobile 6.1 is now the most stable mobile platform available and Microsoft has to take significant credit for the advances that have moved what was substandard and made it class-leading.
On top of WM6.1 O2 have added a few useful pieces of software which complement Windows Mobile very well indeed. First off we have a customised version of SPB's Mobile Shell 2, this adds a finger friendly Today Panel and program launcher, as well as weather info and a Phone profile manager. If you are looking to get quick access to something on the Zest and don't want to pull out the stylus this works very well. Its not as flashy as some OEM shells but actually works much, much better and doesn't overwhelm the device or interface in the same way as HTC's Touchflo 3D shell for example. For the most part the O2 Shell goes unused on my Zest, as I still believe the current Start Menu and Today screen remain the most powerful front end interface I have seen on a smartphone.
O2 have also pre-installed Opera's web browser onto the Zest. This is version 8.65 and its a very good match for the Zest, bringing desktop quality, whole page browsing, however access to the zoom function isn't as good as the later 9.5 version which ships with some HTC devices. Flash support is missing, however Youtube streaming is supported via the rtsp protocol and clicking on a Youtube video link opens the stream in Windows Media Player.
There are some other niceties provided: a caching program for the GPS which speeds up the cold boot satellite lock times as well as a 14 day trial version of Co-Pilot UK for navigation. There's also a Task Manager to allow the manual closing of programs in the background, but this is entirely superfluous on such a stable device. Text entry is handled by the XT9 keyboard, which on first view looks like it will never work. In fact its quite brilliant and has amazing word prediction accuracy, which has to be seen to be believed, because the full width of the XT9 alpha keyboard is less than twice the width of my finger. Finally there is a fairly good RSS feed reader called Newstation.
The Camera software is good and pictures are pretty impressive - a step up from the afterthought cameras we've seen on some smartphones. Of course in low light quality drops off quickly, but with no built-in light source that's to be expected.
One other thing to note is that Zest can be switched into USB mass storage mode, which allows the memory card to be accessed as a native drive on your desktop for quick file transfer and which also means that you can attach it to just about any computer to copy data not just those which have Activesync installed. Every handheld should have this feature its so useful.
Other than the stability of the Zest, the thing that strikes you is how quick and fluid it is. This should be the poster child for Windows Mobile, because its exactly how it should work. There's no sign of the infamous spinning beachball and everything feels snappy and responsive. There's no delay in menus and programs open smartly, even when multiple applications are open there's no impact in performance. Having used Windows Mobile since the days when it was called Palm-size PC this amounts to something close to finding the Holy Grail - an epic quest completed.
Even battery life is good. With 3G enabled, email set to pull every 15 minutes and MP3 tracks looping on continuous play, I was able to use Wifi to browse the web for over six hours before the battery had dropped to 10%. On standby, with screen off, but 3G and pull email enabled I found that the battery dropped by about 1% in two hours, suggesting that the Zest could probably run for eight and a half days in this mode.
I found only one issue when using the Zest, which I think would be a problem only if you were moving from device to device regularly. In order to facilitate better finger interaction the Zest's front is completely flat, with the result that the screen is inset from the front touch layer by about 1mm. This introduces a degree of parallax if you aren't looking straight at the screen. Unnerving at first, but after a couple of hours use I didn't notice it any more and it hasn't been a problem since.
There's even a touch of brilliance about the packaging. The box has been designed so that it can fit through a standard letterbox. Fantastic idea for mail-order delivery. It also explains the rather cool power adapter supplied. This comes in the form of a USB to mini USB sync/charge cable, a small charger unit with a USB socket (just larger than a matchbox) and a folding plug. Unfold the plug. Snap it onto the charger, plug the cable in and you're ready to go. Its even small enough to pocket if you need to carry it with you. For Europeans its even better, as they can leave their two prong plug connected and collapse the prongs for transport. Its the same 1000mA/5V rating used by HTC so you should theoretically be able to re-use existing chargers, however when I tried this there were strange results which suggests one or the other have specific charging circuits. Also in the box are a mini USB headset and a splitter so that you can use both headset and charger at the same time. A 1GB MicroSD card (partially occupied by the Co-Pilot maps) and some manuals complete the package.
Now here's the final surprise that the Zest has for you. And its a nice one for your wallet: the Zest is available on PAYG for £205. That's a bargain in anyone's book. Even better, the Zest isn't SIM-locked to O2, so you can move it freely from provider to provider to get the best deal on offer. If you're looking for a contract the Zest is also available with O2's full selection and is free on most options. Given the price, performance, specifications and quality of the Zest I suggest you run, not walk, to your local O2 store and demand they sell you one immediately.
Asus and O2 have to be congratulated for putting together such an appealing smartphone, which manages to pack a full range of features, outstanding performance and clever design into an incredibly well priced bundle. The only thing I can't understand is why they aren't shouting about this from the rooftops.