Originally Posted by ModelPerfect

To comment from a comic readers' point of view, there were undeveloped lines that make things look sloppy, because they really couldn't go into it. Here's just a few random comments.
(1) It was never confirmed that Cyclops died. They insinuated the heck out of it, but no mutilated body = not dead in movie world (and even a mutilated body doesn't mean much in some cases)
(2) Xavier does die and get a new body in the comic, and could then walk again. His powers are mental, in his consciousness, and that consciousness was moved into his new body = he still has his powers. In the comic, the new body was with the help of the Shi'ar, I believe.
(3) The phoenix saga is WAAAAAYYYYYYY more complex than in the movie...I won't even get into that.
(4) Juggernaut should have died when Kitty Pryde un-phased him into the floor, because his atoms would have fused with the floor = not good. (as a side note, did anyone catch the reference "Do you know who I am? I'm the Juggernaut, bitch!"?)
(5) There are several times in the comics where they use power inhibitors in shackles, so maybe that's what they did which Juggernaut, although that is definitely a stretch (Mystique didn't have the inhibitors, but her powers aren't as dangerous). And why didn't they do anything with the trademarked helmet issue of Juggernaut? It's like the underlining theme of *every* fight with him to remove the helmet.
(6) Rogue and Wolverine both lose their powers at some point in the comic, but of course get them back (as I'm assuming Rogue and Mystique will, since it looked like Magneto was regaining his).
(7) Lots and lots of mutants died in the "mutant massacre" series, so it wasn't necessarily gratuitous what they did in the movie.
(8) Angel was very undeveloped, but probably because they didn't have time, but wanted to use Warren Enterprises and foreshadow for ArchAngel in a sequel...
(9) The needles were all plastic, which means Magneto wouldn't have seen, nor sensed them.

Well, I haven't read the comic in about 12 years, so I'm missing and forgetting a lot, I'm sure, but there's some rardom geek comments.