Campaign was awesome. Spec ops is ok. Multiplayer is awful. Seriously, don't even bother with multiplayer. Everyone sits in corners with shotguns, the spawns are horrible, the maps are designed so poorly they favor all these campers. Some challenges aren't tracked properly. Their skill based matchmaking is totally ridiculous.
What really gives this game a bad review though is all the horrible glitches. Every time the game developers issue an 8-10gb "patch" for something they break 10 more things, while still not fixing the first issue. The icing on the cake here is when they issue patch notes with everything they "fixed", they don't mention any small changes they make. This is usually in the form of multiplayer map design changes, which can sometimes actually be quite big changes. Any AAA game developer that produces a $60 game should at least tell their customers what's actually been fixed and what hasn't. Especially when there's so much that's broken.
My short piece of advice - the game is NOT worth the $60 I paid for it.