xbox live is the way to go imo, mw3 is so fun but between snowboarding and work there isn't much time but this game is such an awesome time waster. add me on live if you want gamertag: RISINGxXxSUN, i play a lot of domination and td, just mention you're from the forum.
I played Campaign mode and it's very similar to CoD Black Ops. Also, it didn't take that long to finish it. I was a little bummed out by that, but I didn't collect any of the enemy intelligence, either, so maybe I was missing some special missions?
definitely agree that the campaign was badass. They usually are pretty short though, mw2 was from what I remember and I don't know if collecting all the enemy intel gives you any special missions? maybe just achievements.