The major thing is the battle system. Yes it will change PVP massivily - People generally are pulled by PVP. But also all other aspects of the game at the same time. Personally i like to play on a PVE server - With a pvp charactor on a PVP server for fun too.
I always liked the Guild Wars way, change servers if one is too populated, and having a character ready for PVP.
	
 


 but I think a lot of you are going to be very dissapointed by this game. It doesnt cut it at all as next gen mmo, not graphically and certainly not via combat and gameplay.