Putting aside the fact that we are talking about a comic book movie which means it is full of cliches and crummy dialog, X-Men 3 was easily the best of the 3.
Director Ratner, not a popular guy amongst fans, managed to crank out one hell of a good ride. There was some sloppy editing but overall, the number of times I went "OH MY GOD! I CAN'T BELIEVE THEY DID THAT!" was higher than any franchise film I've ever seen.
This movie is no-holds barred. I suspect the more you like the comic book the more you'll like the film. Not because they stay true to the comic books (they don't) but because the whole thing plays out like an almost alternative "end game" for the Marvel X-men universe.
Of course, that said, some hard core fans are going to be TICKED by what they did too. They want X-men 4, 5, 6 and so forth. Since there were no plans, they decided to just go crazy and put in a ton of plot lines into a single movie. But if you take the movie for what it's supposed to be, it's extremely entertaining.
There won't be an X-men 4. I feel confident in saying that. There may be spin-offs of some of the major characters. But the X-men ensemble that we've known in the past will never be together again. This is truly a spectacular ending for a really well done movie series.
I give it a 4 out of 5.