I did not like this movie. Or, rather, I thought it was only okay.
Now to get down to the nitty gritty. I am about to give away details of the movie which may spoil your enjoyment of it, so I suggest you not read any farther if you have yet to see the movie.
1) Rogue. She was hardly in it. Rogue is and always has been my favourite X-man. And she wasn't even in the final battle scene! Why not? Because she was standing in line to get "cured".
2) They "cured" Magneto. That was how they stopped him. But the whole point of the movie, and why Magneto was mad, is that most mutants don't think that there is anything wrong with them. They don't need to be "cured". Now, you might say that they should at least make the cure available for people like Rogue, whose mutation is not extremely useful and in fact, only causes her pain. She can't touch anyone without sucking the life force out of them. So for her, the cure is probably a good thing. However, what made the mutants mad, is that the government was using the cure as a weapon. Not against all mutants mind you, but just outlaw mutants (like Magneto and his gang). But I don't think that is an acceptable use of it. Find other ways to contain criminal mutants, but using the cure on them as a weapon is a horrible violation of human rights. It's changing their fundamental nature, changing who they are. That would be like changing someone's eye colour, or hair colour, or something, permanently, just because they're a criminal. And I don't think you have a right to do that. And the X-Men didn't think using the cure as a weapon was good either. Beast resigned over it. BUT then they go and use the cure on Magneto. That, in my opinion, was the lowest thing they could've done. I couldn't believe it. I thought that would have been beneath the X-Men. They're supposed to be noble, you know? Not "the ends justify the means" kind of people.
3) In general I found the movie kind of lacked focus. For a movie that ended up claiming the lives of three X-Men, I thought it lacked a bit of punch.
Now, it wasn't a total loss. I liked a few things about it. For example, I thought the scene where Mystique got shot with a dart and got cured was very powerful. And then Magneto just abandoned her, despite how loyal she was to him.
I also like the part where Kitty is on her own trying to save the young boy mutant from Juggernaut. She can dash through walls and sink through floors and stuff. And despite the fact that she looks about twelve, I thought she did very well.
I also liked the scene where Wolverine told Jean he loved her and then knifed her in the stomach with his claws. That was a gooder. Although that was another thing that I thought was a bit fuzzy in the movie: the whole Jean Grey/Phoenix alternate personality stuff. I know that people who read the comics probably have a good grip on the concept, but I've never read the comics and so found it a bit hard to understand.
I also like the very last scene: Magneto, now just regular human, a very broken-looking, sad old man, is playing chess in the park. With a metal chess set. He is looking intently at the board, and stretches out a finger toward a piece. And the piece moves, very slightly. And then that's the end of the film. Oooohh. Looks like the cure isn't as permanent as they thought.
Anyway, go and see it, but don't expect to be blown away. I personally liked the second one much better. I think it's been the best out of the three.