I loved this movie. It was a fun romp with more mutants than you can shake a stick at, including both the young and old versions of Magneto and Professor X. It had great action sequences, enough character development for me to get emotional, a huge set of Easter eggs for comics fans, and an understandable time travel plot.
And best of all, it achieved a satisfying reset of the movie franchise that should give us new X-Men movies featuring some of my favorite characters.
Certainly there were holes in the script that would seem to contradict things established in other movies, making the original timeline a little unclear. But those were minor quibbles in the face of the monumental task of making a "let's go back and change time" plot understandable to the movie audience.
The plot isn't overly complex, and the fight scenes showing off the mutant powers are clear and wonderful to watch (the best scene is when the mutant Quicksilver deals with a group of armed guards at super speed).
I'm having a hard time writing much more about the movie because it was such a wonderful experience for me, and I don't want to give too much away. It's a big movie and there's a lot going on, especially when the story goes back and forth between the future and the past.