I would have to agree with musicaljon that not a whole lot happened during the movie, but when you try to cram 50 or so comic issues of character building into a 95 minute movie AND have dramatic, earth-shaking events take place, you're probably going to come up lacking.

The problem is that avid X-men fans want to see the real-life interpretations of their favorite comic book characters, so the movie makers HAVE to spend a lot of time bring them all together. Keep in mind that the X-men characters in the movie are necessarily different in a lot of ways from their counterparts in the comics. Fans want to know what versions of the characters they're dealing with, so a LOT of time has to be spent on backstory. After all that, you're left with just enough time to put in a standard X-men adventure formula: Magneto has a gizmo that'll kill everybody, so the X-Men have got to run in, push aside all the racist anti-mutant dogma that's piled up against them, and stop him.

As for problems with the movie: I thought they could've done a lot more with the conflict between Wolverine and Cyclops. Also, it seems like all the characters came ready-made with their comic book names, whereas it would've been much more believeable if, say, it were standard practice at Dr. Xavier's school to pick pseudonyms to protect students' identity for fear of outside attempts to use the school's records to get the names of trained mutants.

Also, it looks to me like Mystique wins. Period. No vulnerabilities?