There's a bug on the first level with the gravity-changing-levers. I managed to make my character disappear when pulling one of them. But I can still hear him walking, probably outside the room somewhere in the dark.
Upon finishing the puzzle it said that I was missing one piece (47/48) and the timer kept on counting. I don't know if it's a bug or if one of the pieces didn't lock properly. Other than that, the game was alright.
1/5. Too many bugs. For example: you don't get forwarded to the waterlevel like with the other levels, sometimes the farm level turns to winter right after you've killed the boss, and the bug that I'm stuck in right now where I can't kill the airplane, but I can do every airborne trick in the world. Too bad that I can't land, else I'd be freaking rich.
5/5 for the story, 4/5 for the gameplay. I'm not a fan of these kinds of games where you alter between characters to complete each level, but I think that you pulled it off well, and with this story it couldn't really be done in any other way. It deserves to be a favorite. :-)