One thing I really enjoyed about the film was how it managed to create realism. By acknowledging the absurdity of the universe and story elements (code names, outfits, etc..), it gave the viewer a reason not to care about those things and focus in on the important elements. Singer knows what matters most--he ends on a chess scene between the two central ideologies. The chess scene is left unfinished...small choices like these are what make this film so special. It is about so much more than mutants--and it knows it.
Overall, the comic films of today could learn a lesson or two from this film--Iron Man 3 is a step in the right direction. You do not have to be a superhero movie to be a good comic book adaptation. As long as you have strong characters and a great script, the action and 'super' elements no longer matter. It was a pleasant surprise to see that this was not a superhero film, but a sci-fi film delving into philosophical questions. In many ways, the original Xmen films (1 and 2) are to First Class what the original Star Trek films are to the rebooted universe.