Both my parents were on virgin mobile and my mom couldn't stand it. Dropped calls, text messages that were never received, and there were a lot of dead zones. I switched my plan on t-mobile to a family plan and brought them on. They've been really happy with it so far.
Also, one other thing - their customer service told me that I wouldn't be able to use an unlocked Nexus 4 on their network - so make sure your phone is usable with them before buying one.
I myself am planning to get myself either a N5 or a MotoG and switch to T-Mobile.