So I saw this over the weekend. Overall I thought it was very good, if a bit uneven. Though its unlikely given how this one ended, I'd really like to see a whole movie of Magneto running around doing spy things.
The first three quarters of this are mostly awesome. The Magneto scenes especially are engaging, with Michael Fassbender more than making up for the acting black whole that is January Jones. There are a few clunky bits of dialogue, but overall I really enjoyed everything before the last sequence. The third act isn't bad per se, but doesn't really fit with the rest of the movie. I don't want to spoil anything, but all the character development that slowly develops for the first two acts is settled in about 30 seconds at the end of the movie. Its jarring, and it doesn't really work, but I guess it was really necessary to maintain continuity with X Men 3.
Criticisms aside, I actually really enjoyed this. The first two acts more than make up for the messy third. Its silly, its over the top, its exactly what you'd expect from an X-Men movie that takes place in the 1960's and stars Kevin Bacon. I wouldn't rush out immediately to the theater to see it, but it is certainly worth checking out.