My opinion changes pretty often on the subject, but on any given day I might tell you the first Iron Man was the best comic book movie ever made. It was extremely well done all around, but let's be honest- there's one reason the movie was so good, and that reason was Robert Downey Jr. There was a huge wow factor that basically lasted the entire movie that they could cast and portray the character of Tony Stark perfectly. That is not hyperbole and I don't use the word perfect often. But there was not a single thing even remotely off about the adaptation of Stark's character in Iron Man. This time around, we don't have the benefit of being amazed all over again. Downey Jr is note perfect again, and if anything has more gravitas to bring to this story. But as an audience we aren't going to sit there and think "I can't believe they got Iron Man SO right!" for an entire movie again. I think because some of that luster is gone, people are mistaking Iron Man 2 as being a lesser movie than its predecessor. I'm here to tell you it's not. It's every bit as good as the first. In some areas it's even stronger, and some of the weak areas are still weak, but overall it fills the big iron boots successfully.
Let's get the negative out of the way right off the bat. There are only three major action scenes, and this movie is long. Many of the criticisms I've read concern the pacing of the movie, accusing it of dragging and not mixing in enough action. I can see being put off by this when you're going into a superhero movie and expecting plenty of explosions and big metal suits. The thing to keep in mind is that when this movie rewards you, it rewards you big time. The action scenes are stellar, even better than the first, with some real imaginative uses of both suits. The animation is some of the best I've ever seen in this style. The only time there's a disconnect because of all the CGI is when they inter-splice a lot of interior head shots of Downey Jr and Cheadle when they're in the suits. It works much better when they have their helmets open and we can see their faces, but obviously in a fight scene there aren't many logical reasons to open your helmet (and they push the boundaries on that front as it is). For me the movie never felt like it dragged, but I will concede that it could have used one smaller action sequence somewhere in the second act to help move things along.
That said, if there's a reason that the movie doesn't drag despite being 2+ hours long without a lot of action, it's because the script and cast are awesome. This movie introduces a lot of new faces but it also goes a long way in fleshing out the returning characters. Justin Theroux, the actor turned writer who penned Tropic Thunder, does a great job with this script giving each character just enough to shine, without stealing the spotlight from the rest of the cast. As for the dialogue itself I'd give him credit if it was due, but according to interviews with the cast the majority of the dialogue was improvised. This was also the case in the first movie (which supposedly didn't even have much of a script to begin with) and was one of the reasons why it felt so fresh and spontaneous. They nailed that feel with the dialogue once again and every performance delivers. Scarlett Johansson is maybe the weak link, but we know she's not really there for her acting chops, and she does perform admirably in the fight scenes. Her performance isn't bad either, just not on the level of her colleagues, particularly Gwyneth Paltrow who absolutely thrives with more material this time around.
The reason this movie works so well is because Tony Stark's support group (specifically Paltrow, Johansson, Favreau, Cheadle and Downey Jr himself) portray such a convincing level of compassion for each other. They are all centered around Tony and will do whatever it takes to hopefully see him through to the end of this. This is a man who is his own worst enemy, but those close to him undoubtedly love him even when he's wrecking their lives, and they know he's worth fighting to save. I think this comes across because of the level of chemistry the cast has with each other off the screen just as much as they do on. Enough can't be said about Favreau's directing to cultivate this level of quality and give his cast the freedom that he does.
Just as in the first movie, the villains are secondary to Tony dealing with his own issues, and that's for the best. Rourke and Rockwell do an impressive job with what they're given, and Rockwell in particular even manages to steal a few scenes away from Downey Jr (no small task). Speaking of the freedom that Favreau gives his cast, Rourke did a great job bringing depth to Vanko's character, making him a bird enthusiast, covering him in prison tattoos, buying his own grill to brighten up his smile, and so on. He also nails portraying the dualism of Vanko being a beast of a man physically but also a genius level engineer.
Speaking of engineering, one thing that this series continues to do extremely well is bad ass engineering scenes. Unlike in the Spider-Man movies where Peter Parker is a cool superhero who happens to be smart, Tony Stark is cool because he's a genius (and an alcoholic). Some of his scientific discoveries in this movie should be hard to swallow, but they have invested so much time and energy covering Tony's intellectual prowess that it comes off fairly convincing. Though I do question his aim when using laser beams in his lab.
Iron Man 2 delivers on all the promise of the first movie. It fine tunes all of its best qualities while still suffering from a few of the same very small blemishes. The villains aren't the most terrifying and the pacing might not be perfect. Otherwise, if this isn't one of those days that I'm telling you the first Iron Man is the best comic book movie ever made, then I could very well be telling you Iron Man 2 is the new king of geek mountain.