Jason Segel, the writer and star of this surprisingly great entertainment, is plagued by melancholia. The film evinces that he likes to feel like a star, at least in the ragtag circle he's amassed of Judd Apatow's expansively talented posse. His character here is a TV musical sting composer who has spent five years adoring his girlfriend, television star Sarah Marshall despite living completely in her shadow like some deposed tsar still doing his seemingly post-middle-age royalty routine for flatterers/bartenders. His journey seems essentially to aim as high as he may in love, not settling for second-best rundowns, and yet to still secure the same kind of neutral lifestyle with a righteous babe with brains, bod and spirit, the challenge of the journey being to realize that that has been his circumstance for five years.

Director Nicholas Stoller seems to surrender to a higher power, so to speak, by being entirely malleable to Segel's material, providing merely a backdrop for the cast to let loose with the goofy, impeccably timed extemporaneous hilarity to which they've become accustomed under Apatow's philanthropic wing. This is indeed the charm of Stoller's elusive touch from the illusory helm, showing an unusual degree of flexibility for a film director.

In subduing any style, the story flows very deeply, mainstream romantic comedy or not, and allows Segel's underdog lead quite an expose of a journey to "forgetting Sarah Marshall," a catharsis of the id which conquers his depressed self-image. Along the way are quirky escapes such as Russell Brand's about-face in my perspective as surprisingly interesting in the role of the title character's new narcissistic rock star boyfriend, Paul Rudd's burnt-out surfer, Bill Hader's ungraceful friend from back home, Davon McDonald's silver-tongued bartender and Jack McBrayder's hilarious rendition of a repressed young religious virgin who's just gotten married. The highlight of the film is Jonah Hill's Hawaiian waiter, who comes to be an awkward, overzealously pushy fan of Brand's. As with Superbad and Knocked Up, he sprinkles fleeting nuances of over-the-top inflections that inspire huge laughs.

As is Apatow's agenda, it's a romantic comedy aimed at guys. All the men in the film get in touch with their feelings, inadequacies and gross idiosyncrasies, rather than safely remaining with the limitations of merely a hot guy who's cool and cocky. And indeed, these films have a much better probability of being satisfactory entertainments, because in spite of their condescended genre they give honest impressions of what it's like to be a horny young guy who seeks the approval of his friends and the women to whom he's attracted. From a film like Forgetting Sarah Marshall, we are fulfilled by the best one can hope for in a film of its kind, and it does that by releasing the leash of social pressures. Jason Segel is funny because he depicts himself as so insecure, but there is nerve in doing that because he imparts to us that there is wisdom in insecurity.