Here’s a solid 9.0 from Game Informer, the same from IGN, and for reference, the absolute lowest, 4/5 stars from Joystiq.
The GI review says the campaign is 10-12 hours long, and I’m guessing that’s on the normal difficulty.
“the best looking console game to date”
“a beautiful, engrossing experience”
“The satisfying gunplay is silky smooth and navigating the environment as a super soldier is a blast”