X3 is a complete disaster. Worst X-Men movie ever. See rant below:
Not only is the Phoenix storyline butchered, but the script rewrites the personalities of its key characters. Since when were Cyclops, Xavier, and Magneto such assholes? Halle Berry's demand for more screentime basically means she shows up in more scenes. Her character has no arc and often says lines that contradict what she said in previous scenes. Rogue has also turned into a whiny sidenote, part of a shoehorned in love triangle, which is disappointing given that the trilogy started from her perspective.
Throwing in as many mutants as you can on the screen, some with powers that would be good if this were an X-Men spoof, but here it's played for absolute seriousness. It also means every character is essentially one note because there's no time to develop anyone. It certainly doesn't help that the movie carelessly removes or kills off half the team from the previous two films. Instead of shocking me, I'm sitting there never sure who I should be rooting for (except for Wolverine).
X3 hurtles through scene after scene to get from one action set piece to another, and at just 93 minutes, there's never any time to process the plot. Of course the movie has to sequel bait with a final scene that suggests everyone will eventually get their powers back. What a way to render the entire movie pointless.
Lastly, this movie cost $215 million to make. Only about a quarter of that money shows up on the screen. The CGI, green screen, and makeup effects are obvious and look horrible. So the movie looks like crap, tells it's story like crap, and treats it's characters like crap. X3 is crap.