I received my G1 yesterday, but have only had a little bit of time to tinker with it.

Response is fairly quick. The touch screen works well, and the track ball is much better than expected. Battery life does seem to be short.

When I enabled wifi this morning, it seemed to knock out the cell connection both on 3G and GSM. The signal here is weak, so I'll have to test this more to see if it is really a problem.

The Shop Savvy application is very cool, though I was only able to find one item so far that it recognized.

I've seen conflicting information on whether the G1 supports only US T-Mobile's AWS 3G (1700/2100 MHz) or if it also supports standard 3G as deployed in Asia/Europe (2100MHz). I'll find out this weekend when I go to Japan.

I called T-Mobile to request an unlock code for my G1. I don't know their exact policy on unlocking. I was expecting them to deny my request since I just got it, but to my surprise they seemed to be okay with it. They may be taking into consideration that I've been a subscriber for several years. They took down the IMEI number and said that they would e-mail the code and instructions within 24 hours. So far no e-mail, so they may not follow through.