I finally watched it on home 3D.
Summary of my experience: Looking at it as derived from the comics, I didn't really get much out of it (kind of like my feeling with much of Peter Jackson's LotR stuff), I had to divorce myself from the source. However, when I looked at it as its own entity happening to "do a riff" based loosely on some familiar storylines and characters, all on its own terms, it was enjoyable enough. [For comparison, I consider "Cap America II: The Winter Soldier" to be a movie that is both excellent on its own terms AND is true to the source comic.] However, considering the hit-or-miss nature of the X-Men movie sequence, this is one of the better ones.
I think Magneto was the closest to what I know of the comic. Fassbender does an excellent job. And I guess McAvoy / Stewart both do a decent job as Xavier. The rest (especially the secondaries, like all the future X-men who die repeatedly), I could take or leave; I really felt nothing with any of that. But Magneto really does come off very much like the comic in that time period + as a total badass; his interaction with the stadium (among other things) was incredible. I remember feeling that way about "First Class" as well.
My favorite scene ends up being very much what I've seen others comment on: "Time in a Bottle," Quicksilver down in the bowels of the Pentagon. I'm not really a fan of Singer, but I think he did a lot with that sequence that resonated and really sticks in your head. Very creative, very fun, very inventive, and finally makes a "speedster" character actually seem interesting and versatile.