I can only speak for San Francisco, but that sounds like an issue with your phone, not t-mobile. Make sure your phone supports LTE and HSPA+ on the right spectrums. My experience with T-mobile in SF has been nothing short of superb, on an unlocked iPhone 5. Super-fast low-latency everywhere I go.
It's comforting to know there's hope :)
Forgot to mention I tried it on half a dozen latest gen phones and even a couple of SIM cards from T-Mobile just to make sure. Even my phone plan was refreshed in the backend to make sure it wasn't some accounting/admin related issue. The radio frequencies probably isn't the problem but it might not be a general issue that appears to 100% of their user base. Just gotta figure out why the hate me :D
