Why are people bothering with going with T-Mobile, when you could just get StraightTalk for $45 a month for unlimited. Straightalk is an MVNO for ATT and TMobile, and uses their towers. So you can save yourself some money going w/ Straighttalk.
Straight Talk doesn't offer AT&T SIMs anymore, unless you want to buy them from Ebay where I think sellers are charging high prices.
Also, Straight Talk customer service sucks. I have to wait on hold for twenty minutes, before I even get to talk to a person. Then it takes another ten minutes, sometimes longer to resolve my problem. Sometimes their customer service lines are so busy, they can't even put you on hold, they just say to call back later.
Right now I actually have Straight Talk on AT&T, but I've been trying out T-Mobile on a prepaid plan. There are some things I like, and some things I don't. So far, I've gotten good speeds on AWS, typically 9-15 Mbps down. On PCS, if I remember correctly, I get 7-11 Mbps down.
Indoor coverage with PCS seems to be improved, my home used to get 1-2 bars, now I get 4-5. I've always had 4-5 bars on AWS.
At school, in one building I get 1-2 bars of HSPA on Straight Talk. On T-Mobile AWS, I got 1-2 bars also, but at one point it did drop to EDGE until I cycled the radio (Airplane Mode). I haven't tested it in a building where I got no service before. Didn't get a chance to yet.
At a local WalMart where I've had issues with both AT&T and T-Mobile years back, Straight Talk gives me 1-3 bars, T-Mobile gives me 1-3 bars.
So T-Mobile indoor coverage doesn't seem to be as bad as it was before, but I haven't taken my phone to everywhere I've wanted to test it yet.
My only problem so far with T-Mobile is at my brother's school. I don't know if they're still working on the tower there or what, but I'll have either good or decent signal, but my speeds will be 10Mbps one minute, but then 0.5Mbps the next for no obvious reason. Sometimes pages don't even load. So I think AT&T wins in network reliability, at least for data.