X-Men: Days of Future Past sends Wolverine back in time to prevent a dystopian future. It is fast paced, has a good story as well as impressive action sequences (especially the one involving Quicksilver). It also shows off new mutant powers, and combines the two generations of the X-Men cast. We also get to see many superheroes die. Although it involves time travel, it smartly avoids any unnecessary jokes about adapting to a different time period. Although the resolution to the climax could have more tension, this is a really good X-Men movie, and is definitely better than The Wolverine (2013).
As before, there is a post-credit sequence.