It depends on what you're after in the game. No matter whether it's PvP or PvE or both, most people would tell you that you will get a lot of game for your money.
If you like PvE, you will love the game, its missions, quests, cooperative play. The problem a lot of people have is that, once the game's end is reached, they find themselves wondering what to do. Of course, one can try other classes, alternative ways of playing, etc. but that's really for another post.
If you like PvP, moving from PvE to that is natural as that is the ostenisble and logical path. There is a hugely loyal and very ardent PvP/GvG audience and, of course, it makes the game more interesting playing against -human- players rather than AI controlled NPCs.
If you like both, so much the better! The game will last a good long while for you. I have to say that for the $50 I spent, I have enjoyed over 200 hours of gaming...and I do not PvP/GvG! I can't imagine how many more hours I could add to that outrageous number if I did!
Are there gameplay issues, balance questions, complaints and suggestions for improvement? Of course but, then again, you get that in any game.