I was thinking the same, after last night. I was stoked that I had "full bars from Northern VA to Philadelphia, with only (3) areas where lost signal (all on the highway), using T-Mobile USA (first time on network). I was even able to stream internet radio feed all the way from Baltimore to Philly, with no drops, on 3.5G.

However last night, 4 blocks from my house, where I get full bars and consistent 900Kb DL, I completely lost signal when I went inside my local supermarket. As soon as I went outside, no more than 10M, I was back on full bars 3G. I'm wondering also how much of a difference with wall penetration T-Mo USA's frequency has, from my current AT&T service.