Its so Free For All in the PVP servers, you can kill ANYONE not in your group. That includes guildmates and friends. No one is safe. This is not a twinkie simple game and you really gotta think about your actions. That fatality might kill the guy but the dot he left on you is gonna get you too ... Then you both spawn in the same spot. Continue the fight or leave it be?
My guild is already making a name for itself and we roll 4+ deep in every zone. We have had a few people who thought because they are higher level could take us out, but we never go out without a fight and it is typically them going down. We finally got a GOOD PVP fight going with a slightly higher level group with two healers. They managed to stay alive better then us, that was such a good fight!