"X2: X-Men United" measures up marvelously. Not only is it much better than the first movie, but it stands so well on its own that you don't need to have seen its predecessor. Relieved of the responsibility of introducing a dozen or so characters (though there are some additions here), "X2" is at full-throttle from the very first scene: an assassination attempt in the White House.

The perp, if that's what you call a blue thingie with yellow eyes and a demon's tail, is Nightcrawler (Alan Cumming), a born-again mutant with teleporting powers and a strong religious streak. His attack is more of a warning than anything else, but it's enough to get the government to reconsider its policy toward mutants -- that is, evolved beings with super powers. They put the matter in the hands of William Stryker (Brian Cox), a suspiciously gung-ho ex-military man who lives to make mutants miserable -- or dead.

First up for messing with is the school for young mutants run by Professor Charles Xavier (Patrick Stewart), a benevolent father figure with amazing mental abilities. He's the leader of the good mutants, who include Wolverine (Hugh Jackman), Jean Grey (Famke Janssen), Iceman (Shawn Ashmore), Rogue (Anna Paquin), Cyclops (James Marsden), Pyro (Aaron Stanford) and Storm (Halle Berry). They just want to live in peace with humans.

The leader of the bad mutants, who just want to live in peace by obliterating humans, is Magneto (Sir Ian McKellen), who begins the movie imprisoned in an all-plastic cell that foils his metal-manipulating powers. However, Stryker is an equal-opportunity mutant-hater. So Magneto and his shape-shifting ally, Mystique (the bodaciously blue and beautiful Rebecca Romijn-Stamos) must team up with their "enemies" for the common mutant good. Hence, the title.

Along with Nightcrawler, there are a few other new characters. Lady Deathstrike (Kelly Hu), who can go one-on-one with Wolverine. A little girl whose scream is so piercing she's every spoiled kid in the grocery store times a zillion. A little boy with a snaky tongue. And Colossus (Daniel Cudmore), who can turn his body into steel. Nothing much is said about a mutant kid whose bangs and glasses recall a certain popular boy wizard, but we shall see.

The great thing about the X-Men comic books has always been how they focus on character interaction as much as on super-powered battles. Relationships that were hinted at in the first film are more developed here -- the Cyclops-Jean Grey-Wolverine love triangle or the sexually frustrated feelings shared by Iceman and Rogue. (Heavy necking could prove fatal since she sucks the power out of everyone she touches.)

Like Sam Raimi ("Spider-Man"), director Bryan Singer really connects with his super-heroes and super-villains. But when it comes to putting together a movie, Singer is not in Raimi's league. The ending, which has about three finales, comes off as exciting, but somewhat overly ambitious. The effects are far better than in the original, but they can have their cheesy side, especially when everyone is running through the metallic corridors in Stryker's lair. Finally, when Stewart gazes off thoughtfully into the cosmos, you can't help but see Captain Picard on the deck of the Enterprise.

Speaking of whom, watching the actor who plays Picard square off against the one who's brought Gandalf to life in the "Lord of the Rings" trilogy (McKellen) in their plummy thespian tones is a ham-acting delight. Jackman, who was supposed to be the next Russell Crowe before he made waste material like "Swordfish" and "Kate & Leopold," reminds us what all the fuss was about in the first place. Plus, he's been cosmetically improved. The mutton chops have been toned down to a kind of full-face George Clooney stubble and the Elvis pomade is now more foxy/wolf-ish. Cumming, recycling his "Cabaret" aach-tung accent as the German-born Nightcrawler, makes an interesting addition. Janssen brings smarts and sensuality to her role while Romijn-Stamos brings, well, if you've seen the previews, you know what she brings.

There is one more litmus test for a sequel. Does it make you want to see a sequel to the sequel? I say bring on "X3."