I thought it was pretty good, but WAY too much humor. I'm not a member of the Camp Police, and I have a (rather unfair) reputatiton of being overly defensive about the Superman movies (some of them anyway) which have similar problems (though not as severe); but it seemed like every single time Tony and Pepper could've had a meaningful conversation, it went off into a series of interruption-gags. Since others don't seem to criticize it as much, I feel there's a double-standard.
Nevertheless, the climax was great (no spoilers here) and some of the cameos really REALLY surprised me.