Living in the UK, I was able to see this last weekend at the local I.M.A.X.
Initial thoughts while walking to the car after the viewing had finished was positive. Its was an enjoyable movie experience, a good sequel build on the incredibly strong foundations of the first movie ( 8.5 or 9/10). However on reflection after the initial impact, I'm now thinking its more like a 7.5 or 7/10 movie experience. With a second watch I suspect this rating might go down even further rather than go up.
As a comic-book movies go, its very hard to complain about either of the Iron Man films. Although the second outing didn't seem to grow the universe particularly. Hammer was way under developed, as was Vanko. No particular character arc for either, and I couldn't quite buy into Vanko's motive for destuction. Scarlett had very little to do (exceptional eye candy though), the one brief(ish) action sequence she had was extremely entertaining and I would have liked to have seen more of the character (in and out of the spandex).
Pepper was just plain ANNOYING. James Rhodes/Cheadle was unconvincing, however I found the previous Rhodes as unconvincing and one of the weaker aspect of the first movie.
The Monaco scene was excellent, as was the final battle. I was disappointed that with adequate screen time Favreau gave for story telling in the second act he never really grew the Iron Man universe, or the main characters excluding Tony Stark. Downey was charismatic and charming as always in the lead role. The effects were also high class, and some of the scenes looked fantastic.
As I said an entertaining movie experience, but not quite as good as I was expecting. 7.5 or 7/10.