From what I've seen, the campaign is certainly good, but the multiplayer just looks like... well... every other Call of Duty game. I'll reserve final judgment for when I play it at a friend's house, though. The games just seem kinda repetitive, y'know?
Then there's the infuriating fanbase (not necessarily you guys, but I mean the hardcore CoD gamers), who tend to be ridiculously arrogant, prone to flaming ANY other shooter, and absurdly try to claim that CoD is "realistic." Seriously, in Cod one can take 4 or 5 shots to the torso from an AK-47, but in real life, a well-placed 9mm WILL kill you. Plus, there's the incessant black-and-grey morality of the campaign, unbelievably depressing plot, and the fact that almost all the awesome characters die brutal deaths.