iphone 3GS. Not great, but slowly improving at actually being a phone. Voice isn’t a big priority for me, I use it primarily for maintaining my corporate/personal email, surfing the web, and playing games.
AT&T service would be the big kicker. I know when I go back to visit my school I have the worst reception ever. But for the most part around where I am in NY the 3G service has improved considerably over the past 12 months.