OMG guys, I must admit this time tmobile nailed it right (at least here I. s. Florida, Miami).
Recently in the last couple of months I have had to switch back & forth from tmobile prepaid service to an AT&T MVNO mostly due to its lack of signal and building penetration. Considering and adding to the equation were the facts that I was using an unlocked iPhone 4S (which doesn't support the AWS band)...
But with my new iPhone 5, tmobile is a keeper. I have been able to keep constant 3G/4G signal almost anywhere I have gone today and even inside buildings where my previous iPhone 4S would drop to edge and with out any problems or dropped calls. I'm so happy, kudos tmobile and their iPhone 5 (my iPhone 5

)