I see we have a lot of whiners.
Anyhoo, the single player campaign is the expected short-but-sweet. The story is delivered on-the-go so you might want to brush up on your CoD4 history.
The Spec-ops are A LOT of fun with a friend, I'd pay $20 for that alone. They better release more of those as DLC or something. The AC-130 one is especially great.
The multi-player is quite interesting. I'm only level 23 right now so I can't judge that much, but I've noticed a few differences. Perks 2.0 are wonderful. There's a crap-ton of weapons and I like all the new additions, attachments and upgrades. There's a lot of new nifty little details in creating your classes. The customizable kill streaks are a nice touch.
Now the maps are overall on a bigger scale this time around it seems, and I kind of miss the stand-offs you'd get in CoD4. But this leads to the need to be more strategic. I think I like it, but I still need to play the game much more to decide about that. It's definitely fun. (and they finally added capture the flag, lol)