If the title is to be trusted (and it probably shouldn't, since the ending leaves the door wide open for another sequel), "X-Men: The Last Stand" will be the third and final part of the Marvel superhero saga. As such, it is a fitting capper to a series that began as a middle-of-the-road comic book adaptation in 2000's "X-Men" and has stayed that way for all three pictures. Not as emotionally resonant, vividly observed or meticulously written as 2002's "Spider-Man" and the first two "Batman" entries—but certainly a step up from hogwash like 2004's "Catwoman" and 2005's "Elektra"—the "X-Men" trilogy has steered a course toward mere fun-while-it-lasts summertime diversions. Sure, there are some underlying themes—the entire series is a thinly costumed metaphor about the struggles for acceptance of the gay community in today's world—but they come as asides to the overstuffed cast of characters vying for screen time and the nifty visual effects that go along with each of their respective powers.

Taking over the director's chair for Bryan Singer (helmer of the original and 2003's "X2") is Brett Ratner (2002's "Red Dragon"), who slides so smoothly into his job that there is no glaring visual differentiation between the two predecessors and this new film. What is a little different is the running time. At a brisk and wholly watchable 104 minutes, "X-Men: The Last Stand" is a full half-hour shorter than "X2." This comes as an attribute because the pacing isn't nearly as uneven and drawn out, but also a debit because not nearly enough time is spent with the extensive ensemble to do any of them the justice they deserve. Without a whole lot of character development and meaty material to sink their teeth into, the actors get by on sheer charisma alone. As for the film itself, "X-Men: The Last Stand" forever walks a fine line between being accessible, mostly satisfying eye candy and feeling like a rush job.

The plot is easier to follow and less convoluted than that of "X2." A pharmaceutical company has found a cure for human mutation, enraging both the special-powered X-Men—Professor Charles Xavier (Patrick Stewart), second-in-commands Logan/Wolverine (Hugh Jackman) and Ororo/Storm (Halle Berry), et. al.—and the more radical group of mutants known as the Brotherhood—leader Eric/Magneto (Ian McKellen), Raven/Mystique (Rebecca Romijn), and John/Pyro (Aaron Stanford), among others. As the X-Men attempt to take a diplomatic stand for their beliefs that there is nothing wrong with them, the Brotherhood prepare for an all-out war, ultimately targeting the source of the cure—a young boy named Jimmy/Leech (Cameron Bright), who is being kept locked up on San Francisco's Alcatraz Island. Complicating matters is the appearance of Dr. Jean Grey (Famke Janssen), a telekinetic former X-Man resurrected from her watery grave as the Dark Phoenix—the most powerful and potentially destructive life force the world has ever seen.

With "X-Men: The Last Stand," screenwriters Simon Kinberg (2005's "Mr. and Mrs. Smith") and Zak Penn (2004's "Suspect Zero") seem to have bitten off more than they can chew. They do a valiant job of developing the central premise and handling the Jean Grey/Dark Phoenix side plot, but in an attempt to cram as many well-known X-Men characters as possible into the proceedings, the scope becomes far too unwieldy for such an abbreviated motion picture. All of the characters are at a constant battle to find individual voices, and few of them succeed. The new characters, all of them potentially interesting—the hairy, blue-skinned Dr. Hank McCoy/Beast (Kelsey Grammer), the winged Angel (Ben Foster), the fast-moving Callisto (Dania Ramirez), and the super-strengthed Juggernaut (Vinnie Jones)—are either cursorily explored or disappointing window dressing. Also fresh to the fold is Ellen Page (extraordinary in 2006's "Hard Candy"), a shining presence as X-Men student Kitty Pryde who deserves more to do.

Many of the returning actors, including Anna Paquin (2004's "Darkness") as Rogue, Rebecca Romijn (2004's "Godsend") as Mystique, Aaron Stanford (2006's "The Hills Have Eyes") as Pyro, and James Marsden (2004's "The Notebook") as Cyclops, are so poorly distinguished that their roles have been reduced to glorified cameos. That leaves only a select few to shine through. Halle Berry (2003's "Gothika"), as Storm, has a bit more to do than before, but the increase in dialogue does not equal out to further character exploration. Hugh Jackman (2004's "Van Helsing") is as rugged a force as ever as Wolverine, landing a few potent dramatic scenes as he must come to terms with sort-of girlfriend Jean Grey's transformation to the dark side.

As Jean Grey/Dark Phoenix, Famke Janssen (2005's "Hide and Seek") is frightening and plausibly maniacal in an extreme turnabout to the heroine she played in the earlier "X-Men" movies. And finally, Ian McKellen (2006's "The Da Vinci Code") is delightfully malicious as Magneto. At this point, McKellen is the only one managing to find further interesting layers to his character, who is torn between his past friendship with Xavier and their current status as sworn enemies.

"X-Men: The Last Stand" is a technically accomplished action-fantasy, likable despite its scripting flaws and thrillingly crowd-pleasing in spurts. For the first time, some of the lead figures' lives are not always safe, and a few surprising casualties are had that bring an added sense of threat to the story lacking in "X-Men" and "X2." A climactic set-piece in which the Golden Gate Bridge is uprooted and realigned to lead to Alcatraz is stupendously mounted—an amazing sight never before glimpsed on celluloid. The big-scale action sequence that follows also boasts real showmanship, putting each of the characters' personal powers to smart use. "X-Men: The Last Stand" is a fast and furious smorgasbord of sound and fury, adding up to little in the long run, but, yes, fun while it lasts. Meanwhile, comic book fans the world over hold out hope that an "X-Men 4" won't be far behind. In the realms of this series, there is still definite room for improvement.