It was good...better than X1 and X3 and Wolverine...
Maybe it is because it is the umpteenth comic movie I have seen, but I felt it was a little underwhelming. Now I feel like Magneto deserved a proper fleshing out, and this movie delivered on all fronts. So I would recommend this for the Magneto back story alone.
I liked it a lot, and I would even enjoy a proper sequel or further exploration of the young X-Men universe. But still, a bit underwhelming for me.
I guess it did defy all expectations though, since the movie looked like shit since it was green lighted and it turned out to be a 2 thumbs up film.
It was quite good. That training montage made me wish this was actually a television series. Wanted more of that. I really like how they easily explained, and hinted with a wink and a nod, number of things like Beast being blue, Xavier losing the use of his legs, his future baldness, Magneto's helmet, the codenames, cerebro, the blackbird, Mystique's aging, etc. And there's something about Mystique and Xavier growing up together that I just really liked.