Seems to work as well as regular sprint service for me. When you make a phone call you hear music or news instead of ringing. They charge a lot for overage. They charge for mms. I can't really say about the data speed because I don't have a browser, just use it for a couple of apps, which work perfectly fine for me.
Call quality is some times vary choppy and unclear, while i have a regular Sprint line which works fine for me,
Seems like they're using a Sprint experimental technology or something that makes its call quality bad.
Data works well though, getting full LTE speeds everywhere, (although no roaming)