Saw it this weekend.
My take - pretty disappointing.
What made the first one so good was the dialogue and the zippy lines of Robert Downey Jr and his interaction with everyone (Pepper and Rhodey especially), and him coming to terms with the new equipment. There were scenes that had you enthralled and laughing, even with no action sequences.
This one is mainly loud and pointless. The great dialogue only comes out in points (with the best ones in the last 5 minutes, and when Samuel Jackson shows up as Nick Fury). Some of the action scenes were good - but it's all been done before. And there was plenty of bad. In my order they were:
1) The Villian. Awful. I mean awful. I like Mickey Rourke...but this portrayal was just terrible. From the lame toothpick in his mouth, to his wanting his bird, even if it might have been the wrong bird, to his awful accent. There was no connection, and no energy here.
2) The Other Villian. Sam Rockwell as the Defense guy was a character we've seen a dozen plus times (the jealous rival who acts tough, even though he isn't, and hires the bad guy who you know is going to turn on him).
3) The fight scenes. Can someone explain to me how Rourke can get hit by a car at full speed and smashed into a wall - and he's 100% fine. He's not a superhero - he just has a suit that somehow allows him to hold on to whips that have an electrical charge. Yet he can get hit by a car and not have a broken back, or spine, or anything? I don't mind suspending my disbelief in these movies, but come on?
4) The action scenes. Ditto with Downey being in a car that is cut in half as it is going 60+ miles an hour and he's totally fine. Dumb, dumb, dumb.
5) Jon Favrou. He had about 5 minutes too much time in this film (and he was in the movie about 6 minutes).
6) Don Cheadle. A great actor...but every scene he was in, he seemed to be saying, "Yeah, they should have never gotten rid of Terrence."
7) The new element. It made no sense. It still doesn't. I'm not even sure what the heck it meant, or how he figured it out, or how he made it, or how it helped him. Ughh
Overall, I would give this movie a C. It's a good popcorn flick, and keeps the energy moving...but the acting was bad, the storyline predictable, the villian(s) terrible, and the comparison to the first makes it seem even worse. I would put it with X-Men 3 and SpiderMan 3 (though likely ahead of both of those thanks to Robert Downey Jr, and Scarlett Johansen who is actually pretty cool in this.
Sigh - hope the movies get better from here on out...though I have my doubts.
And yes, this is an absolute lock for the top 5