It's awesome, hands down.
SO much fun co-op, it's like co-op/challenge where you compete for high score and try to get all items and share at the same time, you can get the other guy killed and there are shared lives for levels so it's not just a fluff game it's a fun crazy romp, many laughs so far have been had.
Already played some peoples created levels and there are over 100 items to collect just on the first 3 levels alone.
This is a first day buy, no doubt. Loving it.