Spoilerificness ahead, Fanface.
The most important thing that this movie does is establish why the most popular color for mutants - other than any of the standard normal human skin tones - is blue. Those of you wondering why there are so many blue people evident in the merry Marvel mutant movie universe will have your question answered.
Short review, because I'm 2 days late with it, having seen it on Monday: Some ridiculous tropes of Hollywood aside, I loved it. It was a lot of fun, and I haven't enjoyed any X-Men movie this much since the first one in 2000, and not just because of my previously stated expectation - the film itself goes out of its way to make everything fresh and new again. I felt like I did when the first Iron Man came out; superhero movies that embrace their mythology this was and toss out anything that doesn't work well onscreen withouth becoming so bloody realistic and serious in the process are a lot of fun to watch. When they fail at this process is when they fail onscreen.
People will argue as to whether or not Kevin Bacon works as a bad guy, but they are wasting their breath, because he does. He totally comes off as dispassionately evil in kind of a foppish and bored way, like someone who gets into being evil because he has a lot of money and spare time, which is what Sebastian Shaw is supposed to be about.
Go see it; lots of fun and cool 60s clothes and music, every character actor that's ever worked in Hollywood is in this thing (should be a drinking game, actually), you will get all mixed up in your feelings about young Magneto and Xavier, and awesomeness abounds.