The Five-Year Engagement, Nicholas Stoller, 124 mins (15)

Jason Segel's latest comedy is like a buffet – you can dip in and out and it never seems to end

Emily Blunt and Jason Segel seal the deal (Universal)

Movie stardom, in theory, used to be defined by some extraordinary quality – a charisma so radiant that you couldn't resist seeing a person's latest film. That's hardly the case with the current breed of US comedy stars: Steve Carell, Bradley Cooper, Katherine Heigl, Paul Rudd .... They seem the kind of people you'd happily invite to a suburban dinner party, where they could be relied on to mix well and not fall over drunk – unless that was specifically required.

The press notes for The Five-Year Engagement say of writer-director Nicholas Stoller that his "comedy is so real that his characters could be your friends and neighbours". Stoller and producer Judd Apatow are in the business of telling stories about people you reassuringly recognise. Here, those people are played by Jason Segel (who co-wrote) and Emily Blunt – and as comedy-night companions go, this duo is more convivial than most.

Segel was extremely good company in The Muppets, where he played eager childlike gaucheness without condescension, and Blunt has always been a striking presence – although her forte is spiky detachment, and here she plays a much softer game. Her character, Violet, is wilful, intellectual, passionate, but still fluffy enough to wear knitted beanie caps. The film doesn't throw any major indignities at Blunt; her open-mouthed OMG-ishness doesn't make her look less smart, just establishes that she has the unpretentious candour required.

But Segel is losing his bristlier edges. Like Seth Rogen, he's been tamed by shrinkage: even when he's in a big pink bunny costume, his dignity isn't impaired. That's the appeal and the shortcoming of such a film: even when Segel's Tom lets himself go (grows mountain-man whiskers, or gets into a flirtatious food-smearing session), you never feel you're seeing his nerves laid bare. Segel and Blunt play a San Francisco couple who postpone their wedding as they move to Michigan, where she gets a psychology fellowship and he puts his chef's career on hold. As they endure decorously, it's the job of various stock supporting goofs to embody humanity's less presentable side (notably, Brian Posehn in the Zach Galifiniakis slot as the hairy, beer-chugging id).

There's never anything seriously at stake: the deferred wedding just seems a handy way to hold off the end credits for two hours. The Five-Year Engagement doesn't quite seem thought through, yet in a way that's its saving grace – this baggy film drifts from situation to situation with free-associative insouciance, its sense of passing time weirdly elastic. That's what moderately smart US comedies aspire to now: to being sketch shows that you can dip in and out of on your plane journey. There's a modicum of charm, intelligence and grace here and, you know, there's no harm in it. But if you felt after seeing this film that you needed to expose yourself to something more toxic – Adam Sandler, say – no one would blame you.

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