Best in series, by far...FAR!!!!
Campaign.
Starts off with a bang, and continues throughout the game with challenging aspects to parts where you just want to throw your controller in frustration because you try repeatedly on Veteran to get past a part...and you fail.......repeatedly. But, to the victor go the spoils. After you beat it, you feel completely relieved and continue the game unto the next challenging point. I must say though, no other game has frustrated me to the point of saying, "to hell with it." Congrats CoD4. You did that! :) But I eventually made it through, beat the campaign. The visuals...stunning! Best yet. Gameplay...smooth! Best yet. Sounds...amazing! Need I continue?
Solid 9.5/10
Multiplayer/Online.
So in depth, that I was completely tempted to throw every other game that I thought was better in the trash. From the upgrades you can make with your weapons, to the perks, to the weapons you receive whenever you rank up to a certain point. Create a Class is the best invention since television. Oh please be in the next installment!
Solid 10/10 in Multiplayer. Don't hate me :)