Bouncing back a forth between this and GoW2. Im not gonna lie, enjoying this a bit more. I just sold 4 more 360 copies basically (took it to an GOW2/H3/GH/RB/COD5 Lanish get together) This game got more play time than most of the other ones listed. Mine was the only copy.
Its simply the best co-op game on 360 right now. It has just the right amount of fun, difficulty, necessary teamwork and that old school arcadey feeling to it.