Great game on single or multiplayer.
The campain was great and on Co-op is fun.
The achivements are very well chosen.
Multiplayer is setup perfect, from being able to send friends videos or snapshots of you owning them to matchmaking with them and ranking up.
I think the matchmaking set-up is a good way to play multiplayer, as this way you can choose who you play ranked games with. Also it keeps the games fair by selecting people with the same abilities to play eachother.
Overall i give this game 9.5 as the graphics and gameplay are not only very good but are, when on legendary, extremely challanging.