Okay I hadn't seen this movie in ages, but since "X-Men Origins Wolverine" is about to be released, I took this past week to watch the three X-Men movies. I think X3 it's okay, it's good, except for two things:
1. Jean killing everybody. I mean, come on! It's too much to handle, even for the general audience. The fact that she kills not only her boyfriend but also her mentor, gives you this feeling of weirdness during the rest of the movie. If the guy that plays Cyclops had other stuff to do, well he shouldn't! That's why he sigened a contract, so he could be available fo the damn movie.
2. This one is a minor thing, but Storm was definetely different from the other two movies, and I don't mean only the hair. Her whole attitude, and that's just so weird. It's like it was someone else. Even the look on her face was different. 
But besides that, I really enjoyed the movie. Some people complain that there were too many characters, but I don't see the problem in that. I loved Archangel and Beast was awesome, specially in the final fight scene. Colossus was great too, specially with the fastball special, or something like that. It was great too see the Juggernaut and Jamie (Multiple man or something) too. I just wished they would have kept Rogue's hair like in the previous 2 movies, 'cause it didn't look so good on her all straight. It was also great to see the Danger Room and a sentinel. So yeah, that's what I think.