OKay first impressions.
Chemistry between Tony and Pepper was almost non-existent. Nothing compared to the first movie. It was almost as if Paltrow wasn't trying. Pepper seemed really flat.
Chemistry between Tony and Natasha was awesome. You could tell he wanted nothing more than to screw her senseless, she totally knew it and acted indifferent. Which of course drove him crazy. You really expected him to just jump her and they start going at it. She drove him crazy and it worked really well.
Happy! There was a lot more Happy in it. Always a good thing to see. Tony isn't really Tony without his supporting cast and they finally gave Happy more air time.
Rhodey...Eh. Totally not impressed with Cheadle's Rhodey. Terrence did a MUCH better job in one and it was sad to see him not there. Cheadle did an okay job, but Howard would have been much better. Though I totally loved that they did include the famous Rhodes/Stark fighting that they do. You get the old married couple feel from them, which you should, and what Rhodey did really makes an impact.
Agent Colsun got more air time! And perhaps had the best line in the movie. Not going to spoil it because it was amusing.
Natasha - Scarlett did a great job with her. I didn't think Scarlett could pull off the cold-calculating type, but she did and it worked really well. Yet she wasn't cold enough that she turned men off, just the opposite. She did a great job with that air of mystery which did nothing but draw Tony to her.
Justin Hammer - Rockwell did a good job with him. Maybe a little over the top, but it worked. Not used to a Justin Hammer like that I suppose.
Whiplash - Mickey Rourke is creepy. Very creepy and he pulled this roll off really well.
Nick Fury - Good for A Nick Fury, but it wasn't THE Nick Fury. Sorry, I'm biased here and as a Nick Fury fangirl, this wasn't Nick.
As said they touched on the Rhodes/Stark fighting that they do, which was good to see because in the first they didn't show anything outside of them being buddies. Rhodey's actions and the fight really got to the heart of their relationship.
LOVED that they touched upon Tony's relationship with his father. How hard of a man Howard was, though granted in the movies he seemed much less of a dick than in canon.
LOVED that they also showed Tony being wasted out of his mind and the problems it caused. I really hope they touch upon the problems with drinking in the next movie. Demon in a Bottle is one of THE defining Iron Man arcs and it really should be brought to the center in a movie. It's not the character if you don't explore his drinking issues.
Liked the overall themes in the movie. Revenge and realizing your own mortality. Two very strong themes and they do a lot for character development.
One thing I really didn't like...Tony and Pepper. I've never seen them as a couple and this part really turned me off. Part of it is because I know canon and part is the real lack of chemistry between the two characters in this movie.
So those were my first impressions. Will probably go see it again.