Saw it last night. Was kind of surprised. It was actually pretty damn good. Obviously Marvel kept Mr, Whedon on a short leash, which was what I had been hoping for. As for the 3D, only fight scenes, or 'splash page' scenes were in 3D, which were kind of jarring. None of the usual forced personalities that Mr. Whedon is famous for (Not to mention that the only 'super girl' was Black Widow, and really, in the 616 Universe, she's near Captain America in physical capacities, and ages slowly due to a Russian super soldier serum.)
Also, 3D hurts my eyes, which might be because I'm still blessed with better than average vision (20/15. Which means at 20 feet out, I make out the same amount of detail people make at 15.) So my brain is trying to process an illusion that I know exists, but my eyes are overcompensating for.