Looking at the majority of posts on this forum you might think... Appalling!
However, consider the amount of Virgin Mobile users each day that don't use this forum because they have no need, they have no problems and everything is working fine for them. That throws a very different spin on things.
Do any of your friends or neighbours use VM, ask them.
Have you checked out the coverage / signal strength (EE) in your area?
If you have VM home media services, you may also get free VM to VM calls. Might this influence your decision?
Is having 4G mobile data important to you? (Virgin Mobile doesn't )
Personally with regard to customer service, I've got no real complaints.
Sometimes an issue can take several calls to get a satisfactory resolve (especially when dealing with offshore). However remaining polite and persistent usually eventually pays off.
Overall I'm happy
If you want to say thanks > click 'Kudos'. Answered your question? > click 'Mark as Helpful Answer' also.