I think the movie was a shade too long and I think they could have re-written the Thor-Iron Man-Cap fight or left it out altogether, just seemed unnecessary squabbling, and there was plenty of bickering later.
I'm fine with Whedon, think he has a sort of television writing genius, I just don't like the vampire-demon-monster genre that he has transformed for more than half his output. Still, he did a great job, both writing AND directing, Avengers. And Shawn, you have plenty of your own talent, and I hope it can flower soon.
I wish the Fantastic Four franchise hadn't phased out and away. This plot would have worked fabulously as a Fantastic Four movie, with the Baxter Building and all Reed Richards' gadgets replacing the Helicarrier. . . .And I would have loved to see how Josh handled that team.