UGH
Great game, graphics, physics engine, controls, story line etc. etc. Copy and paste everything everyone else said into this comment.
BUT
If you BEAT THE GAME, (the last level where you re-collect all the cogs), and you click "Play Again" after the credits, you CANNOT play the secret level that opens in your room. You have to re-beat all of the levels all over again. This pissed me off to no end, as I checked out my room before playing the last level and was like "hey cool, a secret super hard level. I'll come back to this after I beat the last level". And 'lo and behold, beating the game means you can't. I don't have the patience to sit through another play-through of all of the levels just to get to the secret level again. You really should - at the end of the credits - put two options: CONTINUE, or NEW GAME. That way there's no confusion and no butt hurt people like me.
So, just because of that, 5/10 and 2/5.