you get the less than stellar T-Mobile coverage.

My wife has used an iPhone 4 on AT&T towers with Straight Talk for almost 2 years now and other than one time when Straight Talk switched their APN settings and didn't announce it, it's been perfect. All the benefits of AT&T's network, none of the cost.

All the places I mentioned in the thread below where I had trouble with T-Mobile, (St George, Bear Lake, Moab), my wife had good data service using Straight Talk on AT&T towers.