So far the campaign has been pretty alright. Other than the ice climbing stuff and Rio mission (I'm on the second one now), it's been a lot of fun. The snow mission was badass after the ice climbing and before the snowmobile; if there isn't that mission in spec-op, that would suck. Way better than CoD4, too. There are still problems here that CoD4 had, but the weird war porn fantasy this game puts you in so stupid and ridiculous that it's awesome. When Keith David said something like "We gotta secure the Burger Shack", that was kinda awesome.
I don't know how many weapons are in this game, but it seems like there is a shit ton of them lying around. I don't remember CoD4 having both the variety of weapons and the variety of customization on those weapons. Most of them feel great to use, too. Though, I don't understand what dual weapons is all about. I grab one pistol, I try to grab another, it replaces it. But I find a dual pistol set on the ground and then I can use it? ok, sure.
The graphics are also kinda nice-ish, surprisingly. Again, I think that has to do with the locations you're in.
And PC online can be shit, I'll find out later, but single player seems pretty much the same quality as previous games sans lean option (which is a weird feeling since this game is exactly like CoD4 and you have the muscle memory going on).