I have Virgin Mobile and like their no-contract plans. However, if there is ever an issue you're screwed.
Contacting them, getting a live person to help is nearly impossible. I have spent days trying to get through to someone to reactivate my phone. Their automatic menu is horrendously useless and regularly hangs up on people. If you get a live person they try to transfer you to someone else and then either hang up on you or let you hang permanently.
Their customer service is the worst I have ever seen. I have seriously considered dropping them simply because of the customer service.
Review about: Virgin Mobile Phone Service.