I would rate it 9/10. Currently my favorite Call of Duty title because there are so many new features. However, the gameplay mechanics are pretty much the same as any other modern CoD game but I don't care about the gameplay mechanics and the "repeated" gameplay mechanics doesn't bother me, unlike everyone else.
The campaign is awesome; hard, but awesome including the fact that you can customize your loadout and there are 6 different endings for the game. Zombies are awesome too but they are a bit different from your WaW/BO1 zombies and I am still trying to get use to it. Some people like the multiplayer, others hate it (but some of those like this game more than MW3). I am loving the new Mute All feature in the Multiplayer and the Pick 10 system for custom classes.
I am the Thunder Dragon! Xbox 360 Gamertag: TDPNeji
It's not about difficulty. You just invited everyone to give their silly opinion on this game.
I personally think it's a solid, balanced multiplayer experience. Several people disagree because they can't create a custom class with Ghost until level 55. This thread is just inviting people to be unreasonable.