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.
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.
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.
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. 



