Too much to talk about, so I'll keep this brief (hopefully).
Overall, I really enjoyed it! Great action! Great mutant fun! Great death scenes! I enjoyed Kitty and geeked out on Madrox's tshirt (homage to his costume). Juggernaut was cool, but lacked his potential. Angel was ok, but way underused and miscast. I didn't mind Kelsey Grammer as Beast, although I always pictured Beast's personality more along the lines of Jeff Goldblum; quarky/weird brilliant scientist (think The Fly).
I felt Bryan Singer's absence, but that's not entirely a bad thing. It moved quickly and hit all the points it needed to (more or less), albeit often in a blink of the eye. Some of the things this had that the previous 2 lacked were lots of action and good use of mutant powers. You saw a bit in X2 with Magneto stopping the X-Jet from crashing, but that's about it. Here, they amped alot of that up a bit, especially with Magneto! Thank you!
However, X3 was devoid of any real heart. But I'm ok with that. This felt more like the climax the first 2 lacked. There were a handful of negatives and nitpicks, but overall this was a fun, ENTERTAINING movie - full blown comic book come to life, popcorn movie. If they could just meld all 3 films into 1 uber-film, it'd be great!
So, in conclusion, I really enjoyed this movie! It will probably be the one X-Men movie I'll watch the most on DVD. That doesn't mean its a BETTER film, it just means it may rank higher on the rewatchabilitly scale - pure popcorn entertainment. And the bonus scene at the end of the credits not only tied certain characters to how they are currently, recently being portrayed in the comics, it brought up some serious ethical questions.
I'll spare the overall negative aspects....
....but I will share my comic dork NITPICKS:
-Jean loves SCOTT. Not Wolverine. There is no question there. It's that simple.
-Didn't dig on the young Jean's personality; misplaced to the character.
-Juggernaut is not a mutant.
-Kitty dates Colossus, not Iceman (although the "love triangle" was handled quite well I thought).
-Not all mutants are goth with tattoos.
-The younger X-Men needed to play a larger role earlier. COLOSSUS!!!!
-Halle Berry still SUCKS as Storm. It's quite infuriating, really.
-Once again, Cyclops is made out to be a chump. He's the LEADER of the X-Men, people. He should be the hero in the forefront, with Wolvering in the back being the super cool mysterious character.
-Rogue was way underused. Can we please give her Ms Marvel's powers already?
-Pyro controls fire. So why not control the flames other than straight forward? The Iceman battle - move them flames around his ice blast, you idiot! Guess he SHOULD have stayed in school, huh?
-No Toad or Sabretooth.
-No flaming Phoenix effect.
-No Sentinels (the Danger Room does not count)
-Magneto Wooded Mutant Camp felt too much like Costner's Robin Hood.
-Could have been 30-40 minutes longer.
-Wolverine Vs "Marrow": Logan should have just taken the bone shivs as he ran towards him, instead of blocking them. Berserker Rage, baby!
-SPOILER - DON'T READ THIS IF YOU HAVEN'T SEEN: Magneto could have crashed the funeral, held everyone at bay with his powers, and given his respects. Throw in a few X-Defectors to Magneto's cause....I would have flipped out!