Campaign is great...MP is such that I did not even bother to play more than a few minutes...
Had lots of fun with the GAF clan during the beta. Unfortunately the MP game was practically unplayable at launch. Crashes were common in the first 3 weeks or so. When the game became more stable, I think many people have already moved on.
They should have dropped the perks too. It's unfair to new players. Also, same problem with KZ3: Lousy match making, no clans. RFOM MP platform remains the best.
And yes, the campaign is great. Very good blend of action, fun and varied pacing.