I've played on an RP (non PVP) server since I started (Feathermoon), though I've never been able to RP without feeling like a total moron. The good news is, I'd say maybe 10% of the people on that server bother to roleplay at all. And when they do, if it's in public areas, everyone else makes fun of them. Fun times. (Hey, they can't spell. If they could spell, I would not make fun of them. But roleplaying + leet speak does not work for me.)
I definitely would never, ever have a character on a PVP server. I'm not a great player and I know I'm not, but I get by just fine in PVE. The only PVP I find fun at all is Wintergrasp. Well, Alterac Valley isn't too bad, either. Sometimes. But world PVP makes me want to die in real life, it's awful. 😉
For new players/casual players/not very good players (I'm all but new), the changes to WoW are pretty sweet. But even I'm starting to get to the point where it feels like it's getting TOO easy.
Until it really is so easy that it's no longer fun, though, I'll continue to play. I just wish they'd fix Warlocks. 🙁