Best in the series by far.

The gameplay may be better than 3, but it doesn't excuse the fact that you're playing half a game.

While it is a well-made game, it is missing something. Especially near the end.

Has the best campaign of the franchise and the multiplayer is awesome even if it doesn't beat MW2's multiplayer.

Is the game unbalanced? Yes. Is it still an awesome game despite that? Yes. It in fact helps the game than hinder it.