I'm eligible for an upgrade on AT&T and I have the unlimited data plan, but I can't bring myself to get the iPhone 5 with them due to the issues I have had in the past. I use an iPhone 4S, my wife uses my "old" iPhone 4. However, there are times when my data speed lags behind hers (sitting next to one another) and I've always noticed the problem, no matter what phone I use. I have gone to AT&T repeatedly, my SIM card has been replaced two or three times, and I've even received replacement phones from Apple after showing them screenshots of my slow speeds (one was as bad as 0.21 Mpbs Down/0.02 Mbps Up with three bars of service). As a sidenote, if I trade SIM cards with my wife, she has no issues with slow data speeds, so it's doubtful that it's a hardware issue. AT&T has been little help. They always tell me that it "seems fine" and any attempts I've made to escalate it to someone who might be able to see if there's something *technically* wrong with my account have fallen on deaf ears. So, rather than fighting with them incessantly, I'm considering moving to Verizon. The only thing hindering me is my unlimited data plan with AT&T, despite the fact that I never go over ~ 1GB of usage per month. Whether that's due to my poor service or lack of use (from the poor service) is debatable. I'm sure I'm complicating what's a simple thing: If you aren't happy with one company's service, then go to another carrier. It's just that damn unlimited data thing . . .