It's funny how the landscape of superhero movies have changes since the release of the first Bryan Singer X-Men movie in 2000. Back then it was pretty much accepted that if you wanted to make a movie about superheroes, you had to strip all of the comic booky elements out of it. So we got the X-Men in Matrix-style leather uniforms with a sneer about the absurdity of colorful spandex. They all still have their powers, but they feel very restrained.
Since then, we're had a string of successful comic book movies (mostly from Marvel) that embrace their comic book roots with (mostly) comic accurate costumes and bigger than life action. X-Men First Class started moving back in that direction through little things like using the uniforms of the original comic book X-Men and going a lot crazier on the powers, especially with Magneto.
That movie wasn't directed by Bryan Singer though. He left the franchise to make Superman Returns leaving Fox to replace him with Brett Ratner for X3, which resulted in us getting two really crappy superhero movies. Now he's back and with X-Men: Days of Future Past he attempts the herculean task of:
a) Creating a sequel to X-Men First Class that
b) Ties into the earlier X-Men movies while
c) Erasing the damage caused by X3 and
d) Adapting one of the more famous X-Men story arcs
The idea that someone could make a watchable movie while accomplishing all of that is laughable. Certainly none of the prerelease information gave me confidence that it was going to be good. So it was to my surprise that X-Men: Days of Future Past was actually pretty good.
(Mild spoilers after the break, just so you know)