Simple Mobile - What do you know about this cheap carrier?

[magentawave]

I'm going to buy a slightly used T-Mobile HTC HD2, get it unlocked and the use Simple Mobile as the carrier. Apparently they use T-Mobile towers and have an unlimited talk, text and data for only $60 per month.

Anyone know about them? Good, bad, ugly? Is there data speed at least as fast as if I was using T-Mobile as my carrier?

Thanks very much.
Steve