Palgn: Killzone 2 first of all, does not kill any game that has ever been released. The reason for this is that, well, you can't kill something that isn't alive. Seriously though, a game is a game and they are developed around the prospect of entertaining us. And Killzone 2 entertains in a big way.
Guerrilla have defied the claims that they could never reach the visual clarity of that infamous 2005 trailer and they defied claims that gameplay would be lacking. They haven't done anything really 'new', nor have they made a game that redefines the way we play FPS games. They've made a game that sets the benchmark for what level of quality FPS games should aim for, and stands strong against this generations biggest FPS games, proudly presenting itself as a vicious shooter that will grip you by the throat, and won't let go.
With superb aesthetics, a hugely polished single player component, and a deep, class based 32 player Multiplayer component, there is no reason why you shouldn't go and pick up Killzone 2.