I wish the game didn't force you to use cover quite as much as Uncharted did (I like it in Gears of War/Army of Two), but I absolutely disagree that the mutants were a good thing to introduce into the game. They were annoying and felt entirely out-of-place. I hated them the moment they were introduced and, really, their saving grace that makes me not hate as much is they they were relegated to a short portion of the game.