Forgetting Sarah Marshall is a romantic comedy with no qualification, no asterisk and no twist. It's an archetypal, full-blown, boy-meets-girl date movie, and there is no shame whatsoever in that. In the manner of producer Judd Apatow's directorial work (Knocked Up, The 40-Year-Old Virgin), its often uproarious comedic tone is constructed on a foundation of gooey melodrama of the type more commonly found in Patrick Dempsey flicks.

Jason Segel (Knocked Up) is Peter, a broken-hearted and despairing composer, lovesick over his rejection at the hands of his titular television star ex-girlfriend (Kristen Bell, Veronica Mars). Moping and on the verge of a psychotic episode, he looks to make a clean break from his very real depression, picking up sticks for Hawaii and a gorgeous, overpriced resort. Once there, he coincidentally finds Sarah and her new boyfriend, rock star Aldous Snow (British comedian Russell Brand), holidaying on the same island, engaging in acrobatic sexual antics and generally making him miserable.

What separates this film most surely from its moorings is its prevailing undercurrent of weirdness which, while never explicit, has manifest implications for both its likeability and its ambitions for wider success; Peter is a rent-a-composer slaving away on Sarah's pedestrian CSI-lite programme, but his real aspiration is to create a rock opera about Count Dracula using puppets. The songs he writes about vampires, and his nave and embarrassed enthusiasm, help peg him as plainly realistic. Segal helps himself on this front by levelling his characterisation with a taste for the pathetic. The film is hugely pop-culture-aware, and takes easy shots at both Sarah's goofy cop show (which co-stars Billy Baldwin as a wisecracking forensic investigator) and Aldous' over the top, preening brand of radio rock. Chunks of the script are dedicated to looking at how normal people confront fame and the famous, with flashbacks of Peter looking lost on various red carpets as Sarah fronts paparazzi cameras. His eventual decision to get out of TV theme music to follow his vampire puppet dream - not to mention his titular forgetting - can be read as an indictment on the excesses of celebrity culture. Mostly, however fractured and disguised, Forgetting Sarah Marshall is a simple love story, and is better for it.