Something of a black sheep of the Marvel cinematic universe, it's a bit strange to think that so many people dislike Iron Man 2. In some ways, it improves upon the first - better comedy, slightly more consistent tone, something vaguely resembling an actual arc, more fun action, and villains that actually have some thematic relevance to the titular protagonist.
The villains are an interesting point of contention when discussing the film. Most people argue that they are underwhelming, with Justin Hammer being too silly or Ivan Vanko serving as almost too simplistic and second-rate Joker-type baddie. However, there is an interesting component to them together that connects more to Tony Stark. Both are one half of Stark, although without much of a moral compass.
Justin Hammer is literally a second-rate Tony Stark. He's in the same business, dresses the same way, chases down government contracts, and is the only person in the world with an ego to match. At the same time, he isn't exactly known for his brains. His Tony's money and resources, but not his brilliance. Ivan is the opposite. He is one of only a few people in the world who can match Tony's smarts in the technological field. Yet he grew up poor in Russia, and thus lacks the resources of the Starks. Both men have, to various degrees of legitimate, felt burned by the Stark family and their brand. Hammer has lost contracts and frequently loses attention to Tony. Vanko's father was essentially ruined and his family decimated.
Together, they are a reflection. If Tony Stark has a number of problems that make him a less than idyllic superhero (such as raging narcissism and a bit of a chauvinistic streak), the team up of Hammer and Vanko show us just how much worse it could be. They are both versions of Tony without any sense of moral compass.
What makes them work more thematically is that they are on a natural crash course with the invincible Iron Man. Many Marvel villains serve as simply an obstacle or challenge for our heroes to overcome. There isn't really a connection between Malekith and Thor, or Thanos and the Avengers, or Ronan and the Guardians of the Galaxy. Then there are under-explored connections. Obadiah Stane was almost a parental figure and a longtime business partner to Tony for years and years, but our hero seemed shockingly unfazed by the betrayal. Stane's greed made him a natural opponent to Tony's newfound desire to stop selling weapons, but there is so little focus on that clash.
Here, from the get-go, we see how the villains pose a fundamental threat to Iron Man. It works because the stakes are small, as they were in the first film. Where Stane wanted to simply destroy Tony to take over the company for wealth, Hammer and - more significantly - Ivan want to destroy the Stark name. This is significant because Tony's entire objective is to leave behind a more positive legacy than the one he inherited from his father. Every single action the playboy makes in the film is done with the explicit goal of improving and protecting his legacy. The term gets thrown around several times.
So, when Ivan steps into the fold to tear down the Stark brand, it provides us with one of the most natural and organic conflicts in a Marvel film. On a basic level, our villains and hero have goals that are in fundamental opposition to each other. It's done better than it was in the first film, and it was even handled better than it was in Iron Man 3. Sure, it's not given enough attention, and the film is a little too fractured for its own good, but there is a case to be made that the villains of Iron Man 2 are some of the best utilized characters (especially given how underwhelming they are as characters in the comics).
There are problems, of course. Similar to the previous film, Tony is put on what appears to be a character arc, but winds up making all of the same mistakes he always makes and he fails to end up anywhere different. He is the same Tony Stark at the end as he was in the beginning. It is a little messed up that, for all the times he makes an effort to tell Pepper that he is slowly dying, she only finds out because she was on what turned out to be a conference call among him, Rhodey, and Natasha. His narcissism and egotism still get in the way of his relationships, and he never actually does anything to merit a return of feelings from Ms. Potts. (Their romance in these films remains one of the most contrived elements of anything Iron Man related.)
Some tend to complain that the film spends too much time world-building, but it's actually pretty well worked into the central story. The movie isn't really "disrupted" by the set-up of a larger world. In fact, Tony would never have solved the riddle of his problem and, subsequently, learned of Justin Hammer's treachery without the intervention of Nick Fury and his connection to Howard Stark, Tony's father. That, itself, is relevant to Tony's primary issue, which is one of social inheritance and legacy. Even Black Widow plays an important role in uncovering the Hammer plot. Point here being that all of the things that feel like insignificant world-building are actually critical to the main story and theme of the film. One would have to completely rework the film if looking to remove those elements. In actuality, the film doesn't disrupt itself for this world-building to occur.
In regards to the conclusion, battling an army of CGI robots needs to be kept in the context of its release. As common as that trope has become, it's worth remembering that that wasn't always the case. Iron Man 2 kind of kickstarted it. It was the first Marvel movie to end this way, so at the time, it felt fresh and fun. It was action-packed and allowed for some great back-and-forth with Rhodes, who is finally allowed to do something more than just stand on the sidelines and watch. Plus, how they address the casting change is simple, amusing, and efficient. It almost serves as an example of how to move on with actor changes going forward, in some ways.
By no means would one argue that there is much depth to Iron Man 2. Yet, in many ways it improves upon the first film. Viewed through modern standards, it can even be more entertaining to watch. Every Iron Man movie features a similar problem in that Tony gets what appears to be character arcs without actually following through with them, but there is much to like and appreciate about the structure of the sequel. It really is one of the more under-appreciated films in Marvel's collection.
REDUCTIVE RATING: It's good. Underrated.