Its look like a fun game but after floating around Metacritic and major gaming outlets everyone seems to say same things. Basically save points are few and far between and since when you create a game you make a 'online lobby' if you connection goes out your game closes (so said the review at giantbomb). The AI also seems to be of almost no help which makes bosses tough considering its geared to 4 person co-op. Also, people just can't 'drop in' on your games unless they have already beaten the stage you're on.
The price is dropping pretty fast so I'm waiting until about $20 range but unless you have friends who will also be playing for hours at a time I'd say skip this.
