It's a nice phone, although I don't know how much life is left in it software wise.. I don't believe it has the 4.2 update yet and who knows when it will. So if you don't care about the latest/greatest software then it'd be a decent phone at low cost.
I just bought a Nexus 4 unlocked and am on ATT now. I'm much happier, I like the latest software that the Nexus phones (minus Verizon Galaxy Nexus) get.. Many folks I know are going prepaid to save costs too.