1. Brett Rattner: Competent director, bad choice for this movie. Should stick to Rush Hour movies (oh wait, that's his plan).In comparison with the other movies, X-Men 3 is, well, it might be on par with the first one... or maybe not quite. I don't know. Generally I could care less about the X-Men franchise, which is why you don't see me whining about botched (or obliterated) continuity. Speaking as an outsider, X-Men 2 is probably the best comic-based superhero movie I've ever seen. The third movie makes a fine coda to the series, but the story climaxes in X2, and that's unfortunate. X-Men 3 sans explosions wouldn't have much to offer.
2. Far, far too many new characters for a single movie, most with less personality than a thumbnail sketch. You'd get more character development by doing roll call.
3. "I'm the juggernaut, bitch!" This like when The Man Show made that reference to Fark.com, and Adam Carolla winked the the camera for emphasis. Remember when that happened? Of course not -- longtime Fark readers don't even remember it. Throwing a bone to the Internet fanbase is a bad idea because ten years from now nobody will remember what it meant. For that matter, I'm just oozing to find out whether Snakes on a Plane has a shelf-life longer than its initial DVD release. I bet it turns out to be 2006's Home Alone. 'cept for college kids.
4. Plot holes. Lots of 'em, especially of the "wait, _____ could have done _____ and everything would have been fine" variety. Seriously, the characters were so resourceful in the second movie. What happened?
5. Where was the recap? Wow. Here is a sequel that hardly bothers to reintroduce the characters or bring the audience up to speed. If you've seen the other two movies you'll do fine, but anyone having their first X-Men experience will be totally lost.
6. Despite all of this, I actually enjoyed the movie immensely because (let's face it) it's an action-filled popcorn movie, and that's pretty much what I expected.
They leave the story open for continuation, but I'm guessing we won't be seeing X-Men Take Manhattan or X-Men at Bernie's II or X-Men Suit Larry 5: Passionate Patti Does