I was talking to a friend the other day, and he said hew as playing Age of Conan, too. So, I decided to make a character on his server.
Now, I really enjoy PvP when its done well. Unfortunately, most PvP isn't done very well, in my opinion. One of the biggest problems is that most games are based on level. This usually means that no matter how clever, skillful, or whatever you may be, your level 30 character simply cannot win a battle against a level 50 character. Often this means that at lower levels, you're going to be a victim to people who are bored and have higher level characters.
In addition, the crew I usually game with aren't terribly fond of PvP. Only one of my friends I play WoW with is playing AoC, but he rolled on a non-PvP server so I did, too, initially.
My friend on the PvP server said that the current top classes for PvP are Barbarian, Ranger, and Priest of Mithra. Two rogue types and a... priest? Of course, it's the type of priest I haven't played yet.
But, I decided I wanted to try an Assassin. One imagines that an Assassin has to be good at PvP! 
Another problem with PvP is that it usually restricts how you play the game. On a non-PvP server, I look at my feats and wonder, "Huh, what's this do? That sounds interesting...." On a PvP server, you generally have to develop your character in a much more specific way. There is generally one "accepted" build that you should follow for maximum power. It's sometimes frightening to think about the amount of effort put into cracking a game system to optimize power.
Finally, as with most game systems, PvP is rarely balanced at launch. There will be obvious problems and generally a few people will discover subtleties in the system that allow them to gain a constant upper hand compared to other characters. This makes PvP less of a contest and more of a slaughter if you aren't one of the character types that has an upper hand.
So, we'll see how PvP goes. The general feeling is that the developers aren't going to regulate it much at all, so the game will be pretty unapologetically harsh. It could be fun, or it could send me running back to my non-PvP server.