RP PvE is like the "i fail at everything" server type
lol. After playing to 70 on a PvP server, I have to say the environment is significantly less friendly than it was on a RP server. This is an obvious attribute when you're talking about the opposing faction, but I found it mildly surprising that the average PvP player is much ruder, far less agreeable and, well, dumber than the average RP player. There are, of course, plenty of exceptions, but the average person I run into is the type of person I would expect to frequent 4chan.
That said, the element ganking sometimes adds a whole new layer of fun into the game. Sometimes I like the rush of being attacked and retaliating.
Overall, I guess it depends what you're into. If you don't mind a fair number of the people you run into being inconsiderate assholes and you like ganking, then PvP is definitely for you.