The makers of Iron Man 2 decided not to go with a subtitle, but if they had, they could've chosen Echoes. Or Reflections. Or, maybe more in keeping with the rest of the movie, Super-Gloss Mirror Finish. As you can see from where I'm going with this, there's a lot of iterative doubling in Iron Man 2, all of it serving as a very tasty way to put together a sequel that actually has a reason to exist beyond asses-in-seats.
Virtually every major character in the movie is set up as a kind of what-if version of Tony Stark. Superhero stories are largely about what we would do if we had cool powers and the will to ignore the laws of the land, so it makes great sense for a sequel to explore other versions of the protagonist by using side characters as surrogates without sullying the integrity of the character we came to know in the first movie.
There's a character who embodies Tony as military-compliant. Rhodey, Stark's military buddy and tactical conscience, is thankfully given more to do in here than he had in the first film. Rhodey is still the most heavy-handed character in the franchise, a tendency taken to its logical-yet-annoying extreme when he first puts on one of Stark's suits to break up a party that Tony is throwing. Granted, the scene does an excellent job of creating the feeling that a drunken, power-armored Stark is about to make a huge mistake which will cost people their lives, but Rhodey acts in ways that aren't much safer. While this helps to establish Rhodey as the man Stark would be if he were disciplined enough to want to follow orders rather than write his own, it also felt a whole lot like Movie Logic, as Rhodey can't quite seem to figure out his motivation here.
Don Cheadle takes over for the role that Terrence Howard filled in Iron Man, and though no one is likely to notice it, Cheadle quietly pulls off the best acting in the movie. He manages to play Howard playing Rhodey, replicating Howard's verbal and physical mannerisms completely, while also managing to slip effortlessly into the verbal give-and-take that Howard seemed to have some difficulties with. There are some great character moments between Cheadle and Downey Jr., particularly during the climax, when the audience is reminded just how much fun it might be to pilot a personalized flying tank once you've worked through your angst at the consequences of doing so.
There's a version of Tony that explores what he'd be if he were less competent and, coincidentally or not, ethically bankrupt. Justin Hammer wants so hard to be as smart and capable and shmoove with the ladies as Stark that it's tough not to feel at least a little bit sorry for him, even when he's being a totally immoral scumbag. Being so comparatively pathetic keeps him out of the realm of mustache-twirling villains and puts him closer to being someone with whom the audience can empathize. He's not an everyman - the only character in the entire Iron Manverse who comes close to that label is Happy the chaffeur - but keeping one of the two antagonists grounded in mundanity helps to emphasize that this isn't a narrative about good and evil so much as it's one about conflicting agendas. That's a nice improvement on the first movie, which attempted a similar feat but failed due to its villains being, well, totally villainous rather than simply possessed of an opposing set of goals to the protagonist.
Sam Rockwell wears "slimy, somewhat desperate sleazebag" very well. He sells Hammer's inadequacy and arrogance at the same time, managing to pull off the latter at the same time that he makes it obvious that Hammer doesn't realize just how much he's compensating for a lack he can't recognize in himself. In every scene in which he's matching wills with other characters, which is every scene in which he's talking to anyone other than his personal toady, he's entirely incapable of getting his way and just as incapable of understanding why that is. It's not a super-nuanced performance, but Rockwell clearly has fun with it without needing to wink at the audience.
There's a third character who shows us how Tony would be if he hadn't been born with so much privilege and, definitely not coincidentally, in a country other than the United States. Iron Man 2 isn't as blatant about its exploration of the theme of America-as-world-cop as the first film was, but through the character of Ivan Vanko we get to see that Stark's proclamations about the ease with which he has ensured United States supremacy on the world stage aren't as true as he claims, even beyond the personal difficulties that he's experiencing as a result of his stint as Iron Man. Thankfully, we don't get any simple answers to the questions raised here, and the ramifications of what Stark is doing continue to ripple outwards. For every problem he solves, he creates at least two more, a principle which Vanko is more than happy to embody. Vanko's role here neatly buttresses that of Stark's father, both of whom serve to show that Stark's world extends beyond charisma and racecars and supermodels, despite how much he'd prefer it otherwise.
Mickey Rourke is pitch-perfect as Vanko, making what should be a completely ridiculous character seem like the most naturalistic person on screen. The secret to this is his choice to eschew any kind of theatricality; we only get to see small hints of what's going on under the surface, a display of emotional control that's much more frightening than any amount of bombast would have been. It's easy to believe in the methodical, elaborate plans for revenge which he eventually unveils. Rourke also injects a few lighter moments into the character, particularly with the restrained smiles he shows when other characters are trying to intimidate him. Really, after this, it seemed like the most obvious move in the world to cast Rourke as a supervillain, something which should've happened much sooner than it did.
The characters from the first film haven't changed much here, and the overall narrative feels like another story arc in a continuing series, neatly picking up where the last episode left off and moving the characters through different relationships with each other in a mostly organic fashion. That makes sense for a comic book movie. What's interesting is how little the rest of the movie follows comic book tropes.
War Machine, Whiplash and Black Widow are never referred to by those names. Iron Man is only referred to as such for the purpose of using the weight of that name to manipulate people and the press. Very little of the plot revolves around anything to do with hidden identities, and when it does, it doesn't matter much to the protagonist. We don't even see Iron Man doing anything heroic until near the end of the film. The theme of how much being a superhero costs the person behind the mask is important for a good chunk of the film, but here it sidesteps the usual focus on how having a secret identity affects the hero's personal relationships and skips straight to the physical cost, something which most superhero stories gloss over. All of this shifting of focus does a good job underscoring that the Iron Man of this movie franchise isn't like other superheros, in that he inhabits a larger world than most heroes and has a more troubled role in that world. He's more super-soldier than Superman, the kind of hyper-deterrent that Watchmen tried to make of Dr. Manhattan and failed, in spite of seeing just how godlike the scope of the latter's power is. Iron Man is the more believable protector-cum-superweapon, precisely because we see how the aftereffects of his actions affect the world rather than zooming in on his superpowers themselves.
All in all, Iron Man 2 succeeds at hitting virtually every target it aims for. It's an action movie that keeps the scenes between its action sequences at least as much fun as the 'splosions, a comedy that keeps its pacing tight between its dramatic beats, and a special effects fest that bursts with charisma and fun writing. It's not quite as perfect as its predecessor, which is still the finest example of the straight-ahead superhero film that's yet been produced, but it works its additions to the franchise into the story without needing much in the way of dull exposition or Movie Logic. It's not trying to be momentous or literary, but there's just enough pain under Stark's metal helmet to keep the character compelling in the face of all the lighthearted banter and robot action.