Here are my two cents...and keep in mind we have another Virgin cruise planned for this summer...
We found that the excursions were not great (this was for our greek cruise). We actually got refunded for 2 of them because they were terrible (tour guides got us lost, bus didn't know where to go...etc).
I also found the staff less professional. I LOVE the diversity and no limits on showing tattoos, piercings, hair, etc. But service shouldn't be compromised. We witnessed entertainment staff using foul language with one another, ignoring guests, and not knowing key information (where venues were, restrooms, etc.). I just got the sense that maybe the training for staff isn't as rigorous as other lines.
Overall I just felt like Virgin is GOING to be great one day. But they're working out kinks that other established lines have had more experience with.