Primary school teacher Julia Fitzpatrick (Jennifer Garner, right) falls for Dr. Harrison Copeland (Patrick Dempsey) in the romantic comedy Valentine's Day. (New Line Cinema/Warner Bros. Pictures)

Those who can't stand Valentine's Day rail at its commercialism, sentimentality and tendency to make uncoupled people feel like failures. Those who recoil at the romantic comedy Valentine's Day, the latest from director Garry Marshall, will likely despise it for the same reasons, with one addendum: it's a genuinely bad movie.

Director Garry Marshall seems so tickled that he's scored so many stars that he forgets to direct and sits back to watch his pals play charades.

Valentine's Day is an ensemble film that features the dreamiest of dream teams: Julia Roberts! Jennifer Garner! Bradley Cooper! Ashton Kutcher! A pair of Jessicas (Alba and Biel) and Taylors (Lautner and Swift)! It's got both McSteamy and McDreamy, and some seasoned vets (Shirley MacLaine, Hector Elizondo) for cross-generational appeal. That's only a fraction of the high-profile cast, whose characters cross paths and collide in various permutations over the course of 12 hours or so on Valentine's Day in modern-day L.A.

Unfortunately, you may need a scorecard to keep track of the famous faces onscreen – and their storylines. No sooner have we met Reed (Kutcher), a florist who proposes to his sweetheart, Morley (Alba), on the bouquet industry's busiest day of the year, than we're plunked into bed with Julia (Garner, whose natural goofiness is wasted here), whose shady doctor boyfriend (an alarmingly orange Patrick Dempsey) promises to make up for the fact that he'll be spending the evening in the O.R. (Surprise! Dempsey's character is a surgeon who "fixes broken hearts" for a living.)

There's a lusty 20-something couple in the throes of new romance (Anne Hathaway and Topher Grace), a kid with a schoolboy crush, teens on the verge of losing their virginity and septuagenarians whose 50-year marriage hits a speed bump when a long-buried secret is revealed. Oh, and a military captain (Roberts) who's flying back from Afghanistan to celebrate the special day with her special guy.

It is possible to deftly juggle such a sprawling cast and their convoluted narratives: the late Robert Altman did a superb job with Short Cuts, his own ensemble ode to Los Angeles. Even director Richard Curtis managed to provide satisfying payoff in his 2003 film Love, Actually, a stickily sweet offering that's an obvious precursor to Valentine's Day.

But Marshall seems so tickled that he's scored such a cavalcade of stars that he forgets to direct and instead sits back and watches his pals play charades. The tone zigzags wildly, from Borscht Belt slapstick to gooey sappiness to Serious Social Issue commentary, and the actors gamely try to maintain an even keel. Swift suffers the most — her flaky, pro-chastity motormouth seems to have sprung from a terrible Saturday Night Live sketch. As her lunkhead boyfriend, Lautner is equally broad and bad.

Jason (Topher Grace) and Liz (Anne Hathaway) are among the many lovebirds in the film Valentine's Day. (New Line Cinema/Warner Bros. Pictures)

Marshall also leaves no blanks to fill in. A cross cut to a scene between Cooper and Roberts on a plane, for instance, is preceded by a stock shot of an airplane exterior. After a flower delivery truck gets rear-ended and spills its load on the freeway, we're left gazing at the musical card our 5^th-grade moppet bought his crush, crushed under car tires as it sadly croaks out a tinny version of Michael Bolton's When a Man Loves a Woman. Think the message will ever make it to our young swain's paramour? Marshall barely lets us wonder.

Even worse, the director gets caught up in self-referential moments. Valentine's Day is riddled with winking nods to Marshall's canon: at the arrivals gate at LAX, two men hold signs marked "Unger" and "Madison" (that's The Odd Couple's Felix and Oscar); Anne Hathaway's "adult phone entertainer" does business in front of Pretty Woman's Beverly Wiltshire Hotel.

Perhaps these in-jokes would've been cute if Valentine's Day didn't already feature distracting meta-content: a regrettable side effect of these casting choices is that you're constantly reminded of the prior associations between actors (Kutcher and Grace co-starred in That 70s Show; Cooper and Garner are Alias alumni; and so on).

For all those issues, Valentine's Day's biggest weakness is its script. It's not just that screenwriter Katherine Fugate relies heavily on icky platitudes that wouldn't even fly on Hallmark cards, or that the pathetically few non-white characters come across as crass, racist stereotypes (Queen Latifah plays a tough-as-nails Mammy; Jamie Foxx a smooth playa; George Lopez's Alphonso is part Tonto-like sage, part archetypal Magical Negro). The worst part of Fugate's screenplay is how woefully out of touch it seems. Without giving away too much, let's just say that when your set-up for a heavily foreshadowed revelation that two characters are in a same-sex relationship evokes The Crying Game, you should probably rethink your approach.

Near the end of the film, Elizondo's character shares the profound notion that real love is about appreciating all the parts of a person, both good and bad. It's a concept that Marshall would likely want viewers to apply to Valentine's Day. But no matter how hard you try to love this movie through its worst, it's hard to find enough better to balance out the equation. As any good therapist would advise you, when there's not enough good to outweigh the bad, there's no relationship left to save. Valentine's Day, it's over.

Valentine's Day opens Feb. 12.

Sarah Liss writes about the arts for CBC News.