I had to manually reselect tmobile as my network operator under settings -> wireless networks but after that I got data. Was pretty smooth and painless. Also data roaming was off so you might want to change that back if you had it enabled before (I did and I'm almost positive I won't get data roaming charges).
Its an awesome update. Pinch to zoom works where it said it would. It's *MUCH* faster. I think they unlocked all the ram. Boots faster, homescreen apps thing flies in noticeably faster.. and yes this is comparing to reboots before the update and its speed. Under version it says 2.1- update1 now. I also get HSDPA in my apartment (check by going to *#*#4636#*#* then phone info. It'll say it under network type.. run a ping test it seems to switch to the mode automatically after some sort of data has been sent.. my guess is to save battery life). So overall it looks great.