Bought MW3 finished campaign in like 2-3 Hours then finished it on Veteran before I went to sleep. My verdict campaign is really crap and reminds me in its shitness of Star Wars: The Force Unleashed 2. Played online for about 2 days was alright. Then came back a few weeks ago and everyone online was running round with sniper rifles quick snipping which made me give up on playing it. Black Ops in my opinion is a much better game campaign wise and online wise as the campaign actually made me care about the characters eg. Woods and Bowan. Online the guns are much more equal. Halo 3 is a better online game than MW3 and it came out ages ago and didn't have as much hype as this game.
The game is pretty fun when your with friends. The campaign is pretty terrible though in my opinion. Honestly I have enjoyed every CoD apart from MW2 and CoD3 since CoD2 came out.
Compared to the others it's pretty shit. It as a few good modes but that about it. Took me 3 hours to complete the story mode on the hardest difficulty. Give it a try, you may like it.
It sucks ass! Black ops is still better, and the main reason why it sucks so much is sometimes you can't connect to the servers because it says your "net is strict" and it's so random because you can be playing it for days and get the random mesg. A lot of people on youtube complain about it.