I like AP 

. The way I see it, it lets people who don't want to PK not have to PK. In a way, it is rewarding people for not PKing, but the only way to not get the award of "invincibility" is to insist that you don't want it by killing others. I hate the mentality that if something doesn't benefit *you* outright, then it's a bad update that isn't go for the server. Plus the different nick name colors make the server look nicer—much nicer than the nick names did before.
The staff has already added some ways to tie AP into the game (e.g. getting more AP while at church) and it's likely they will continue to do so as they release more major updates.