Grade: C+

First we had the Farrelly brothers’ terrible take on “The Heartbreak Kid.” Now we have what amounts to the Apatow factory’s riff on the same Neil Simon/Elaine May comedy. Of course, it’s not billed as such, and the storyline isn’t precisely the same (it’s more like “The Heartbroken Kid”); in tone, moreover, “Forgetting Sarah Marshall” is—as you might expect—very much a “Knocked Up” knock-off. But however you analyze it, the movie is just another link in the line of cinematic sausages that the Apatow assembly line has churned out to the apparent delight of a large segment of the moviegoing public over the past few years. This one has some good ingredients, but they’re mostly in the side dishes rather than the main course, and they’re not tasty enough to make the whole thing worth ordering.

The script comes from Jason Segel, who also stars as Peter Bretter, the sad-sack, semi-slacker composer of the score to a hit TV cop show. Peter also happens to be the long-time live-in boyfriend of the program’s gorgeous blonde star, Sarah Marshall (Kristen Bell), to whom he’s played willing second fiddle as she’s sucked up the public limelight. Unfortunately, she abruptly dumps him, sending the poor schlub into an emotional tailspin that brother Brian (Bill Hader) tries to pull him out of by suggesting he take a vacation. So Peter goes off to a luxurious Hawaiian resort that he can’t really afford.

Unfortunately, Sarah’s also there with her new boyfriend, a deceptively spacey British rocker named Aldous Snow (Russell Brand). Fortunately, vivacious hotel clerk Rachael (Mila Kunis) helps out by providing our messed-up hero with an expensive suite gratis to impress his ex-squeeze. Can romance between them be far behind? Peter has other adventures as well, most notably with an overeager waiter (Jonah Hill) and a zonked-out surfing instructor (Paul Rudd). And hanging over it all is the question of whether he’ll be able to get over Sarah, or whether she’ll recognize what a good guy she’s lost and play on his leftover love to break up his budding relationship with Rachael.

There’s some very funny stuff in the movie. Kunis, who was such a sparkplug playing against Ashton Kutcher on “That 70s Show,” makes an agreeable impression, even if her character’s attitude switches seem dictated by script requirements rather than logic. Hader has a few amusingly deadpan moments conversing with his brother either in person or via computer screen. William Baldwin and Jason Bateman get solid mileage out of the periodic clips from the TV show in which they supposedly stars with Sarah; one can imagine the bits being sharper, but they work on a fairly obvious level.

And best of all is Brand, whose portrait of the completely self-absorbed but oddly likable Snow energizes the picture whenever he appears, despite the fact that the guy is unbelievably laid-back. The fellow’s blithe unconcern for anything that doesn’t directly impact him comes to seem positively justified when the people he’s dealing with are themselves so vacuous: his refusal to take their problems seriously is a perfectly proper response to the fact that they’re hardly serious people (and, in the end, even more self-absorbed than he is, and with far less reason).

Add to that the fact that Brand makes Snow hilarious, which is something that Segel and Bell don’t manage to do with their characters. God knows that under Nicholas Stoller’s permissive direction, Segel tries desperately to turn poor Bretter into a lovable lug—he bawls, he brays, he mugs, he even disrobes from time to time, Will Ferrell style, to give the movie that shot of raunchiness that’s become an Apatow trademark. But in the final analysis the desperation is all too evident, and Segel ends up coming across like the less talented younger brother of Daniel Stern, whom he definitely resembles. (The business about Bretter’s Dracula musical—especially the big finale in which it’s turned into an off-Broadway puppet show—is particularly lame.) As for Bell, she can’t do a great deal with a role that makes her pretty much a cold, calculating fish. By now Hill and Rudd are reliable card-carrying members of the Apatow stock company, and they get some easy laughs. But one need only think of Preston Sturgess’ slate of character actors to realize that Apatow’s isn’t in the same league.

Like all the product from this source, the movie is nicely appointed, of course—Apatow’s long past the point of having to scrounge for budgets. Cinematographer Russ T. Alsobrook makes good use of the Hawaiian locations, and the production design (Jackson De Govia), sets (K.C. Fox) and costumes (Leesa Evans) are all top-drawer.

But “Sarah Marshall” proves all too forgettable; the movie provides some decent laughs along the way, but you’ll probably not feel too badly about breaking up with it when the credits roll.