Don't trust the reviews you see. 1.6 out of 5 is absolute garbage. I never played MW2 so to me it doesn't feel like a DLC as a lot of people have said in their reviews. Reviewing MW3 on its own....
Campaign: 4/5
It's a great story, just very quick to play through. With that said, I never even bought the game for the campaign.
Multiplayer: 4/5
The game has great movement. Amazing gunplay, and really decent graphics. Personally I like the settings and the enormous amount of attachments and weapon options, although, at times it can feel a little overwhelming when going through so many different class setup options. Once you've played for a couple of hours you'll quickly find what works for you. On the down side, SBMM is a little painful to deal with, although I tend to always have a positive K/D unless there's real sweats in the lobby.
As for the rest, I can't be bothered. I am only here for multiplayer, which is the best I've ever played! Great playlists as well, with small map moshpit and the ability to choose which game mode you want. Some maps feel massive and it's no longer the 3 lane system. To be fair, it hasn't been that for many years now.... so for everyone who moans about it, just needs to adapt or move on.
This game receives way too much hate for how good it is.