Like the happy monkey inside an empty vessel, this is a reasonable puzzle game with a supremely good multiplayer game inside of it. Many various modes of play for multiple players gives this game much more life than it's simple, yet challenging single-player campaign.
For the single-player element there are series of increasingly difficult puzzles which you must navigate. These border from the boring to the insane, and the learning curve is rather steep in this game's case. However, most of the puzzles are able to be conquered with no real trouble.
The multiplay element is in fact more daunting of a task to explore, since there are so many games and modes which can only fully be taken advantage of with more than one person. If you have the full set of controllers, great. But otherwise, you may feel limited in some minigames such as Monkey Fight. You'll have fun, but you need to have four controllers to fully experience this game.
All in all, a very good game. I give it a 9 rating.