About ten years ago romantic comedy started to merge with raunchy comedy  an early example was "There's Something About Mary" after which I've never felt quite the same about hair gel. Judd Apatow as writer, producer and director has become a deft exponent of the resulting amalgam, though in this case he and the gang (Nicholas Stoller, director, Jason Segal, writer and lead actor, and others) have not been quite as deft as they were in "Knocked Up", which had a semi-serious plot. Here we have Apatow lite. Peter (Jason Segal), a rather ineffectual, self absorbed composer of TV show music whose improbably glamorous girlfriend of five years, the eponymous Sarah Marshall (Kristen Bell), suddenly leaves him for Aldous (Russell Brand), an English rock star with a vast ego and voracious sexual appetite. Peter takes a vacation at the Turtle Bay resort in Oahu, Hawaii and guess who's there too? Yes, it's Sarah and Aldous, noisily in the next suite.

Rachel (Mila Kunis), the gorgeous desk clerk at Turtle Bay, unaccountably takes an interest in Peter, who is overweight, depressed and generally unappetizing. But things bump along from there and there are plenty of funny scenes, before the denouement, which involves a rock opera production of Dracula using puppets.

A number of the actors are from US television and handle the challenge of parodying their TV roles very well, Kristen Bell and Mila Kunis in particular. The absurdly pretentious Aldous is given some of the sharper lines, which has the effect of making the rest of the cast look pretty dumb. But the laughs keep coming. Like "Seinfield", it is a comedy about nothing (almost) but the lines are good and the scenery is nice. Turtle Beach Resort will be happy. We didn't get to see turtles breeding though, despite them being "in season". Apatow and co are entertaining, if somewhat on the slight side, and the raunch is kept under control, despite Apatow's determination to remind us of the importance of the penis.