Review in a Hurry: The prequel none of us thought we wanted turns out to be more of a fun time than anybody expected. A return to form for the X-flicks, this semi-prequel/reboot remembers above all else to be fun, without any gross bastardizations to the source (like the portrayal of Deadpool in the Wolverine movie).
The Bigger Picture: Best not to worry exactly how this new movie fits in to the existing cinematic continuity, as it features some crowd-pleasing, deliberate shoutouts to the Bryan Singer films while also containing significant contradictions.
Probably the best way to look at it is as a Star Trek-style alternate timeline; First Class opens with the same scene that began the original X-Men, then veers in another direction that suggests what Marvel comics fans might recognize as a "What if...?" tale.
Setting the story back in the '60s doesn't make for as much change as one might expect. The X-Men are still technologically way ahead of the rest of the world, and have their blackbird jet years before anybody else. But you know what decade it is by two major signifiers. Villain Sebastian Shaw (Bacon) has a swinging sense of decoration Austin Powers would envy, while his master plan to create the Cuban missile crisis and accelerate it into nuclear war is total retro-Bond baddie. It even builds credible tension despite the fact that we know how it all worked out.
Meanwhile, we get the usual Malcolm X-MLK allegory between Charles Xavier (McAvoy) and his newest friend Erik (Michael Fassbender), both of whom will be Professor X and Magneto by movie's end (not really a spoiler, folks, seriously). Placed back in time, the debate over violence versus integration feels more specific to civil rights, while talk of atomic power having brought the mutants into being is a nice throwback to sci-fi movies of the era.
Perhaps surprisingly, the dominant relationship onscreen is the dynamic between Xavier and Mystique (Lawrence) who in this telling are adoptive brother and sister. She's also a bit more modesty-prone than her future self, but it's her arc that's more important than that of Magneto, who's pretty much out for blood from square one (and not without good reason—audiences may well cheer the deaths of his first few victims).
Other standouts in the cast include Lucas Till as psycho-jock Havok, and Nicholas Hoult as the ironically punished Beast. Less impressive is January Jones as Emma Frost, whose periodic morphs into a human chandelier make more of an impression than the lines she delivers. Fans of character actors, meanwhile, will see a veritable who's who among the armed forces brass: Michael Ironside, Ray Wise, Glenn Morshower, James Remar, Rade Sherbedgia...as far as movie militaries go, these guys are decorated veterans.
Overall, though, it's Fassbender's coming-out role as a true movie star—rather than blending into the character, as he's done so well in Hunger and Inglourious Basterds, he exudes leading-man charisma. Director Matthew Vaughn did this for a pre-Bond Daniel Craig in Layer Cake, and he knows what he's doing now.
The 180—a Second Opinion: There's one uncomfortable climactic moment of similarity between this and X-Men Origins: Wolverine, above and beyond the use of significant historical nuclear crisis. Mercifully, it is handled better this time.