I came into the movie having unfortunately stumbled upon the spoiler that pretty much everybody knows about now. I'm still pissed about seeing it. (It was ruined by some jack-ass who was posting his comments in the comments of virtually every article posted on this (awesome) site.)
I tried not to let this knowledge affect my feelings about the film. I hope others will be able to do the same. I never for a moment thought I was getting the Mandarin from the comics. Based on the Marvel Comics movies to date, I don't know that he "work" if he was exactly the way he was in the comics.
First off, the acting was exactly what I expected. RDJ was excellent. I really liked the upgraded role of Pepper and Happy just made me... well, happy. He added some great comic relief to the beginning of the film. And "Mandarin" was just awesome. Sir Ben was so good in this role, even after we discover who he's really playing. And Killian was much better than I expected. It made it much easier to accept that he is behind the Mandarin.
For me, the film is defined by little moments. The reaction from Pepper when she discovers that Tony is not inside the suit. The interaction between the kid and Tony before he drives off. The scene where the Mandarin shoots the guy in the head. There were many of these powerful, defining scenes and I felt they gave the film the soul it needs to finish the trilogy. And I was especially happy to see that this was an Iron Man film without interference from the rest of the Marvel Universe. It needed that. It kept it personal.
Overall, I was really pleased with the film. Honestly, I'd rate it the best of the three. The film was much more about Tony Stark than Iron Man, but RDJ pulls it off. I kept hoping that he would change. Y'know, be more compassionate. More likeable. But Tony was Tony. RDJ was given a powerful film to run with and he did.
I'll end with this. I don't think of Iron Man 3 as a superhero film. It has enemies with powers and all that stuff, but it has much more going for it. While I felt that the film stepped further away from the hyper realism other films have offered, it offered a personal journey of one man who truly takes on much more than he can handle.
I'm looking forward to the 4th installment. We all know it's coming. I just hope Shane Black will direct it. I really loved this film. Ironic, since I hate Iron Man in the comics. I'd rank this among my best Marvel films to date and I'm even more pumped now to see the rest of the Phase 2 films.