Jandy Hardesty’s review published on Letterboxd:
I figured I'd go ahead and watch this before The Avengers comes out, since I had missed it in theatres the year it came out. "Missed" isn't the right word. I heard bad things about it and opted not to go. And yeah, this movie is pretty boring, especially for an action movie. There are only like two and a half actual action scenes in it.
The first hour or so I was kind of bored stiff - there were some good ideas in there, like Tony being poisoned by the thing that's saving him, but the film just uses it as an excuse for him to wallow in self-pity (somehow he manages to be arrogant AND self-pitying at the same time) and do ridiculously stupid things.
It picked up in the last third, after he met with Nick Fury and Black Widow (as herself, I mean, not as office drone Natalie), and I perked up a good bit, but even so. The good bits (callbacks to Howard Stark, a fun performance by Sam Rockwell, decently choreographed if overly digital-looking fight sequences) couldn't save the dismal script.
Easily the worst of the Avengers lead-up movies I've seen (the only one I'm missing is Incredible Hulk). Not only is the script a mess, but it's deadly dull for extended portions of its overlong running time, and that's pretty much the worst sin a film like this can commit.