I had the iPhone on ATT for six months, the only thing I got was dropped calls and restricted use. I will say its the first SMARTphone my wife has ever used and she really liked it. So we dumped ATT, paid our ETF fees, both of them and I got her an iPod Touch and she is happy enough.
I will NOT get another iPhone, I would get one for her and her small business but thats a different matter.
Not 100% sold on the ThunderBolt, but I did choose ThunderBolt Fanboy, way more than an iPwn.