Only done a few hours of campaign so far but I find it at least as good as the previous versions, better in some areas for sure. Haven't played MW2 in a while (GOW3 took center stage for a while) but it seems the MW3 graphics have been improved a fair bit, very realistic in some areas, almost too real looking.
Have to wait for my son to get home to continue on the campaign so I'm off to play online for a while, hopefully they've done as well there.
Steve