The cover+regeneration mechanic makes the game boringly easy and repetitive, the art direction has you trying to pick off these grayish enemies against grayish backgrounds with grayish squad mates "helping" you, the AI is crap, those sequences with the Troika thingies are crap, what I saw of the story was drivel, and the whole "enemies coming out of the ground" schtick was dumb. Fun, GoW is not.
They didn't even had the basic good sense of making the whole thing campy.