I will say this:
There is a scene in the novel (I won't say which one) that has the potential to turn the movie from a wonderful, moving jaw dropping piece of storytelling even better than any era of the comic book (Save perhaps the best Clermont storylines) into a merely okay popcorn movie. If it's in the movie, it's a blink-and- you'll miss it moment, but it absolutely destroys a certain character (and no, I don't mean the obvious one.) I keep wishing that scene was filmed and then cut out, since the X2 novelization didn't mention Jean Gray's sacrifice. Sadly, though, the offending scene is also in the junior novelization too, so most likely it stayed put.
On the other hand, if said scene had been cut out, then it would take either twenty minutes or so more of screen time to bring the movie to a logical conclusion, or else the ending would have to be changed to an unacceptable outcome. (Well, unacceptable for the suits at Fox. {Most} Fans of the comic would take it completey in stride)