In my review for 2000's "X-Men," I wrote about its inevitable sequel: "Look for it to be released in 2002. You can mark my word with a capital X." While I underestimated by a year, it was as obvious then that there would be a sequel as it is obvious now that there will be a third chapter in 2006. Returning to the director's chair is Bryan Singer, who has a clear understanding of the Marvel comic book series and treats his cinematic adaptations with the respect and overall faithfulness they deserve.

In terms of budget, scope, special effects, and action set-pieces, "X2"—a stupid title that should have been called "X-Men 2"—considerably outshines its previous installment. However, while there are a wider array of inventive, standout moments here, the film lacks the faultless pacing and focused storytelling of the original. Taking all of the final elements into account, "X2" stands as a worthy enough follow-up, but just a notch less successful. In this case, bigger doesn't necessarily mean better.

Picking up where "X-Men" left off, and doing no favors for those unfortunate viewers who have not seen, or do not vividly remember, the first flick, Wolverine (Hugh Jackman) returns to his family of fellow mutants after a trip to learn about his origins leads to a dead end. Wolverine, who has retractable claws between his fingers and the power to heal quickly, is reunited with Professor Charles Xavier (Patrick Stewart), the head of the Mutant Academy they live at who can control minds; Dr. Jean Gray (Famke Janssen), a practicing telekinetic; Cyclops (James Marsden), Jean's jealous boyfriend who has laser beams for eyes; the weather-controlling Storm (Halle Berry); Rogue (Anna Paquin), who can steal people's life force; and Iceman (Shawn Ashmore), Rogue's new beau who can freeze things.

When a maniacal, power-hungry general named Stryker (Brian Cox) sets out to manipulate their abilities and put an end to the mutant race, the X-Men must team up with their villainous counterparts, the metal-dominating Magneto (Ian McKellen) and shapeshifting Mystique (Rebecca Romijn-Stamos), to put a stop to Stryker's misguided plans. Brand-new mutants this time around include Pyro (Aaron Stanford), a confused teen who controls fire; Nightcrawler (Alan Cumming), a blue-skinned, reptilian teleporter; and Lady Deathstrike (Kelly Hu), a razor-nailed vixen being controlled by Stryker.

A full thirty minutes longer than its predecessor, "X2" is nothing short of ambitious in the amount of characters it has to juggle within an even larger framework, but it doesn't always pay off as handsomely as it should. Despite being more or less a low-key, character-oriented introduction to the series, "X-Men" never once became tedious or strained. "X2" ultimately does not manage quite as well; the opening 40 minutes are way too exposition-heavy, its energy notably lagging until Stryker's forces raid the school. The overlong climax is also bogged down by a collection of key plot points that feel rushed and not as cohesive as they should have been.

It is the ensemble cast, some dazzling effects work, and a few of the action scenes, then, that make "X2" a flawed movie still worth seeing. Nightcrawler, who resembles more of a Disneyfied creation than a true X-Man, is tolerable thanks to his awe-inspiring ability to teleport himself through a process known as "bamfing." The effects work in bringing this to life is wildly complex and nothing short of marvelous, particularly in the opening sequence, in which Nightcrawler sneaks into the White House and almost assassinates the President. Another action set-piece, an aerial chase involving missiles and Storm-made tornadoes, is nothing short of genuinely thrilling.

The cast take their roles seriously, and it is in their decision to play things on a realistic level that leaves the viewer actually caring about them. Hugh Jackman (2001's "Someone Like You") once again leads the way with macho bravado and a tender heart as Wolverine. One of the major strengths of the original was his sweet relationship with the insecure and frightened Rogue; it is disappointing that it is not accurately recaptured this time around, and that Anna Paquin (2002's "25th Hour") has fallen into the background.

As leaders Professor X and Magneto, Patrick Stewart (2002's "Star Trek: Nemesis") and Ian McKellen (2002's "Lord of the Rings: The Two Towers") memorably recapture their tricky dynamic, playing off each other with equal parts sympathy and menace. Famke Janssen (2002's "I Spy") and Halle Berry (2002's "Die Another Day") have found their roles of Jean Gray and Storm widened, with Janssen particularly impressing in her poignantly developing love triangle with Wolverine and Cyclops. Speaking of Cyclops, James Marsden (2001's "Sugar & Spice") disappears for nearly half the movie and, strangely, is not missed; his is the most underwritten central mutant character. Rebecca Romijn-Stamos (2002's "Femme Fatale") is as slick, devilish, and sexy as ever as Mystique, who is also afforded more screen time and a deeper character.

Best of all, perhaps, is Kelly Hu (2003's "Cradle 2 the Grave"), viciously indelible as Lady Deathstrike. Every moment she is on screen pulsates with life, even when she is not doing anything of note, and Hu makes the most of a small part. She also is given the movie's most unforgettable sequence, by far, an elongated fight opposite Wolverine near film's end that has to be seen to be believed.

Written by Michael Dougherty, Daniel P. Harris, and Bryan Singer, "X2" has so many positive characteristics—not the least being how fun it is once things get going—that it is a shame the storytelling is so muddled at times. The movie is deceptively simple and overtly complicated at the same time, and apart; its two halves, mixed together, make for what is an occasionally very good, and occasionally frustrating, experience. A major moment in the finale is also just plain sloppy, as the group is confronted with a problem Iceman should have been able, or at least have attempted, to fix, but never steps up to the plate to use his freezing gift for the good of everyone else. Even if it is nowhere near the quality of 2002's seasonal starter, "Spider-Man," there are enough original and fascinating portions of "X2" to make it a respectable way to start off the slam-bang, effects-heavy summer movie season. At the same time, there is a nagging sensation that, with another writing draft or two, it could have been even better.