Based on the rabidly popular young adult novel by Stephenie Meyer (the first in a four-part series), "Twilight" begins well as a teenage slice-of-life, then takes a sudsy turn into romantic melodrama. That one-half of the lovebirds is a vampire, over one hundred years old but forever in the form of a studly 17-year-old boy, may have avid filmgoers feeling a sense of déjà vu. That would be because the superior Swedish film, "Let the Right One In," was released just a few weeks earlier and tells a very similar and more affecting tale between two 12-year-olds. If "Let the Right One In" is very much an R-rated horror picture, it is also undeniably sweet. "Twilight," by comparison, is a commercialized PG-13, going after a predominately female audience who don't mind that the story they are being fed is sappier than an elm tree in spring.

When her mother decides to travel around the country with her new husband, a minor league baseball player, 16-year-old Bella Swan (Kristen Stewart) willingly uproots herself from her Phoenix, Arizona, home and goes to stay with her father, Charlie (Billy Burke), in the small, overcast Northwestern town of Forks, Washington. Bella is nervous about how she will fit in at her new school, but quickly makes friends with a nice group of classmates who welcome her with opened arms. Even so, she is more intrigued with reserved outsider Edward Cullen (Robert Pattinson), a pretty, pale-skinned hottie who attends school with his adopted brothers and sisters Emmett (Kellan Lutz), Rosalie (Nikki Reed), Alice (Ashley Greene) and Jasper (Jackson Rathbone).

It's attraction—and possibly love—at first sight for Bella and Edward, but when he miraculously saves her from getting hit by a car, stopping the automobile with nothing but his strength, she knows there are secrets he is hiding from her. After Edward finally reveals his true identity to her, Bella takes the news of his undead ways in stride. However, when she becomes the target of a darker, more dangerous group of vampires led by James (Cam Gigandet), Bella has no choice but to leave her dad behind and go on the run with Edward and his family.

Directed by the radically uneven Catherine Hardwicke (2006's "The Nativity Story"), "Twilight" sparkles in its first act, and then loses its way big time. At the onset, Bella is portrayed as a bright, intelligent teenage girl who may be in a rough situation by moving in with a father she hasn't been very close to, but remains refreshingly mature about it. Free of the typical brooding adolescent histrionics often represented in cinema, Bella is a fresh and likable protagonist. The friends she makes at school, including Jessica (Anna Kendrick), Angela (Christian Serratos), Mike (Michael Welch), and Eric (Justin Chon), are also wonderfully written and free of stereotypes, each one nicely individualizing themselves from the others. Bella's initial interest in Edward after they are paired together in their biology class is also understated and effective. So far, so good.

Once Bella and Edward take their relationship to a higher level and become a couple, the film all but forgets about Bella's other friends in lieu of a ham-fisted love story, a clunky thriller subplot, and more cheesy dialogue than you can roll your eyes at. Bella, up until this point, has been a level-headed and efficient character, but she loses all of her sense and ambition the second she falls for Edward, agreeable to throwing her ambitions away in exchange for a chance to be with an immortal vampire. "I'm not afraid of you," Bella tells him, "I'm only afraid of losing you." Later on, he declares, "You are my life now." They've only been going out for a few weeks, mind you.

What do these two people see in each other? Screenwriter Melissa Rosenberg (2006's "Step Up") fails to provide an answer, instead going the route of a mostly chaste Harlequin romance where development is downplayed while lines such as, "You're like my own personal brand of heroin," take precedence. Edward may be a "vegetarian" vampire, as he calls it—he only drinks the blood of animals—but that does not excuse the fact that he basically is taking advantage of a girl who is a century younger than he. When Bella discovers Edward in her bedroom in the middle of the night, and he tells her, "I like watching you sleep," the results are more skeevy than romantic.

The beautiful cast, bar none, look like Abercrombie & Fitch models fresh off the showroom floor. At least most of them are good actors, and they'd have to be to make the script work whatsoever. Kristen Stewart (2007's "Into the Wild") is an unconventional choice to play Bella in that she seems like too much of a progressive, liberal thinker to make her character's dimwitted actions believable. Try, she does, and Stewart pulls it off. As Edward, Robert Pattinson (2005's "Harry Potter and the Goblet of Fire") has a magnetic physical presence, but sometimes stumbles with stilted line readings. The supporting cast is strong across the board, with Taylor Lautner (2005's "Cheaper by the Dozen 2"), as Bella's childhood friend Jacob Black; Anna Kendrick (2003's "Camp"), as Jessica; and Christian Serratos (TV's "Ned's Declassified School Survival Guide"), as Angela, standing out.

Filmed in Oregon and Washington State, "Twilight" is rapturously shot by cinematographer Elliot Davis (2005's "Lords of Dogtown"), taking full advantage of the natural, untainted beauty of the Pacific Northwest surroundings. Effects work, with a preference for wire stunts and greenscreen over CGI, is top-notch. And, in a surprising twist on what is expected, Edward's family welcomes Bella into their home, even attempting to make her dinner despite not being able to eat themselves. Little details like this, and a complete revisionist take on conventional vampire lore, suggest a creative ambition that does not carry over to the romance between Bella and Edward. By the end, Bella comes off seeming like a foolish schoolgirl straight out of the 1950s, ready to give everything up for the creature of her dreams. By not being able to wholeheartedly rally behind their relationship, the picture crumbles around it. "Twilight" holds an archaic, pre-feminist mentality far more disturbing than any of its tame horror elements can boast.