All right, I admittedly have some complicated feels about this movie which I've been tussling with over the past day and a half or so. Most of my wiggling is centered around the last ten minutes or so, though, so let's just get down with what works. (As always, I have no respect for spoilers, so 'ware.)
1) The Mandarin was. Freaking. Awesome. My eyebrows went up into my hairline when I first heard that he was going to be the major villain of the third movie, 'cause, whoo-boy, there is a lot of racism in them thar hills. Turning an unintentional racist caricature into an intentional racist caricature deliberately and cynically used by a white villain in order to provoke fear is brilliant. Excellent trolling, Marvel.
2) Literally every single thing about Pepper Potts. I was a little worried that she was going to wind up fridged, but introducing Extremis would have actually made it palatable to me if they had decided to go that route. (No body, no death, baybees. It's the comic-book way.) But Pepper getting to be an honest-to-God superhero in her own right was, like the treatment of the Mandarin, completely brilliant. I'm going to pretend that Tony's making-everything-better in the last ten minutes mostly meant him speed-reading enough books on the human genome to keep her from going 'splodey while still letting her remain an awesome fire goddess. Did I mention that I liked Pepper in this movie? I really, really liked Pepper in this movie.
3) Breaking the hero down to his most basic components and then building him back up. This is actually a textbook heroine's journey, which I love. Let's face it, if you slot the Avengers into a Five Man Band format, Tony's The Chick, not Natasha.
The only two things I didn't like:
1) I'm still torn about removing the arc reactor. I know, it fits the movie's theme of Tony shedding his crutches and realizing that he's a hero because he's a hero, not his traumas, but...the arc reactor.
2) They explained the rabbit. I was perversely hoping they wouldn't. :)
LET BLOCKBUSTER SEASON BEGIN!