The first game I ever remember having a new game plus was Chrono Trigger, and they handled it superbly. Being able to beat the game at almost any point with a different ending was brilliant. I always wished they did this with Final Fantasy.
Kratos does real good at killing, but lacks in some other areas. He tends to have nip-slips, he gets entire gore bags stuck in his beard, and his sense of humor is less than impressive.