When you watch it, make sure you watch through the end credits.
Slant Magazine gives it 3 1/2 out of 4 stars and says,
The series that Favreau began and Black has now brilliantly reconfigured has served to help resurrect the superhero genre in the wake of twin catastrophes Spider-Man 3 and X-Men: The Last Stand, resurrect Downey, an actor of tremendous seduction and force, as a natural leading man, and now resurrect Black as one of Hollywood's most assured and clever hit makers. And yet, the most appealing thing about Iron Man 3 is its ambitions to not merely resurrect, but reinvent the nature of such elementally safe entertainments.Salon.com says,
The third and purportedly last of Robert Downey Jr.’s adventures as the armor-clad but increasingly vulnerable Tony Stark features one of Downey’s most nuanced performances, arguably a lot better than the movie around him, and keeps him separated from the physical and emotional protection of the Iron Man suit for extended periods.Moria didn't much care for it, pointing out the betrayal of comic book canon. Slate says, "Iron Man 3 has jettisoned both thoughtfulness and credibility to fulfill its contractual quota of kabooms." Rotten Tomatoes has a critics rating of 78%.