So far, so good. I got my first-ever cell phone a couple weeks ago and am doing this exact thing: Nexus 4 + T-Mobile pre-paid plan. I'm on the $60/month plan on the page linked above by whichdan, but will probably drop to $30, because I just don't use many talk minutes. So far, I don't have complaints with the service.

*edit DON'T have complaints. Accidentally an important word.