Chose this over a Nokia N95 because people told me the Nokia's battery life was poor, this appeared better but in practice is equally dismal. Last about 2 days on a full charge if you don't use it at all!! Last about 2 hours if your surfing the net (wap only), using windows media player or the built in GPS function (hardly great when your stuck up a mountain and it dies?!) . Oddly windows media player has no function to turn off the screen if your only listening to music thus zapping vital battery life.
Constantly freezes when using the internet and voice call quality is poor. Not bad for texting as uses Microsoft outlook style. It is a pain having to integrate the phone to a computer before it will recognise it and can play havoc if you do this with more than one PC - duplicate phone numbers appearing, files disappearing and ringtones changing.
Alarm function is rubbish - can only choose between the phone noises - maybe a beep (keypad?), a bop or t-mobile introduction which is totally inadequate at waking you up in a morning. (that's assuming it hasn't run out of battery power over night!)
My biggest fear is the phone may be a lemon as I have lost data on 3 occasions.
First was when, for no reason?, it refused to send / receive or even open the programme? texts - T-mobile could not advise a fix that I decided myself was a major reset - meaning all data in the phone lost.
Second was when it decided to wipe all my programmes, photos and music off the 2gb storage card?
Third (probably no means the last) is the sim card packed up just before Christmas.

I would like to swap but there are few options in the pda bracket with gps which incidentally is good once the programme you are using finds a signal (and that could be 10 minutes!)

I had a Compact II before upgrading to this Compact III.
Like the Compact II it is a PDA based Windows Smart Phone - built buy a company called HTC and re branded and sold under the T-Mobile name.
This phone has a touch screen, Windows 5.0, Word, Excel, Powerpoint, Internet, email, Media Player, PDF Viewer, Sat Nav, 2mp Camera. Oh... and a phone.
If you have a Compact II in my view its not worth changing and paying money for. If you're thinking of getting a Windows Smart Phone with Sat Nav for the 1st time - then this is the one.
Loads of features, easy to use and well priced, or free if on a contract with T-Mobile.
The one major thing with PDA based phones - they are not designed as a phone first. There is no substitute for real buttons!
The reception is not very good at home - well, non-existent, but that has more to do with T-Mobile's coverage in my area and not the actual phone.
I use the sat nav a lot and the GPS receiver is built in to the phone, as opposed to the old Compact II where it was a separate unit.