It is 2.5D, it is very pretty, it is meant to be played with up to 3 buddies and it has physics puzzles. It's good.
It is difficult to find a flaw with this platformer since it keeps things small and simple, and it is difficult to call the smallness and simplicity a flaw since the game costs appropriately. You get a choice out of 3 players and you move to the end of the level, using your physics-based powers to defeat enemies and navigate hazards. The visuals show off a variety of well-designed environments and the colors are pretty. The little voice acting there is is good. The story is simple but does not feel lacking since the game is not story driven.
I suppose the one problem is that this game is tailored towards co-op, which means you need friends and ideally 3 XBOX controllers (though the keyboard is totally serviceable) to experience it fully. Without another player, I am not entirely sure how I would have solved some of the puzzles. Anyway, the game is fun and adds enough new content on top of the first game to justify its existence. Get it if you don't dislike platformers, especially if it's on sale.