From IGNs review
Modern Warfare 3’s campaign commits the biggest sin possible for a globe-trotting action thriller: it's boring. What had the promise to be an intriguingly spun web of mystery instead ends up being a dusty cobweb you'd find at the back of your shed, clinging onto 15-year-old garden toys you once had fun with. It's a pale imitation of the past, made up of underbaked story moments that clash with attempts to introduce new open combat missions designed to encourage player freedom that instead fall flat on their face. Yes, the gunplay is still great and the graphics and sound design are top-tier, but I couldn't help but feel I was playing a shinier, less subtle version of something I've played too many times before. If this is the quality we've come to expect from Call of Duty campaigns, maybe it's for the best if a year or two is taken to reset and raise this low bar back to the heights of old.
From my detailed review yesterday
Finished it in about 3 1/2 hours, worst campaign I have ever played in the COD franchise and I spent $100 on this
4/10 and I think thats generous