More of the same, but decently balanced and surprisingly addictive....
Having also replayed the campaign, I got a little bit better taste for it. It's not great, but it's not bad either, even though it's a rehash of the past two Modern Warfares. Spec Ops is okay too, though nothing mind blowing.
As for the MP, it's pretty much the same as MW2, but with a lot of the BS taken out. I never really find myself rage-quitting unless a hacker shows up, which unfortunately happens a bit too often. P2P matchmaking over proper dedicated servers is still a pain, but the game doesn't suffer from as much lag as MW2, and it's easier to find games.
Killstreaks are toned down and can be dealt with easier now, and there are no super-overpowered weapons any more, even though akimbo machine pistols can be a pain.
All in all, I can't say I regret spending $30 for 200 hours of entertainment, so while the game itself isn't great as you have played it all before, I've gotten my money's worth, and then some. CoD is a consumable product for sure, but it's still worth it as long as it's fun to play. You get more hours out of it than most other games before it becomes boring.
Now let's await the arrival of Black Ops 2, and keep the cycle going for yet another year. Whoop.