Engadget has published the most complete review about the T-Mobile G1 that I have read.
The G1 isn't going to blow anyone's mind right out of the gate. Looking only at the hardware, there's nothing here that's particularly impressive, yet nothing that's particularly bad (though the GPS needs some work). It's a fine, solidly designed device that has enough style to please most users -- but it won't win a ton of beauty pageants. Think of it this way: if it were running Windows Mobile, it'd be a footnote in HTC's history.
Well, after reading this review I have to rethink a little bit the whole idea of buying one. There is not any doubt in my mind that Android will be a tough competition for Windows Mobile and for the iPhone. Android has the energy of a teenager while Windows Mobile has not been changed a lot in the last 2 years. At least I do not see there the adventure that I see in the Android any more. If you think about, Windows Mobile still alive because programmers of many other companies are creating amazing applications that compete well again iPhone. But the OS by itself still almost the same since WM5. The problem is that Google/T-Mobile did a huge mistake by picking this HTC design to start the battle against Microsoft and Apple. That together with the few things that I read in this review has made me to reevaluate my plans about buying one. Let’s see what happens in the next few weeks.