Take This Waltz, Sarah Polley, 116 mins (15)

This Canadian romantic drama trundles along sweetly — but do lovers really speak like this?

The romantic deck is somewhat stacked in Canadian drama Take This Waltz. On one hand, Margot (Michelle Williams) is married to a charming guy, Lou (Seth Rogen); he's cuddly, they love each other, they wake up entwined every morning to share baby talk and bizarrely violent endearments: "I want to put your spleen through a meat grinder." Problem is, Lou spends all his time cooking chickens (he's writing a chicken cookbook; it's what he does).

On the other hand, there's Daniel (Luke Kirby). He's sexy, but sensitive too; an artist shy of revealing his talent to the world, he makes his living wheeling a rickshaw round Toronto. An affair seems written in the stars: Margot bumps into him by chance in Nova Scotia, and wouldn't you know it, he turns out to live right opposite her.

A powerful, and knowing, streak of fantasy emerges in hothouse visuals: the film is phenomenally atmospheric, cameraman Luc Montpellier pumping up the reds to evoke the erotic hum of a steamy summer. One highlight is a funfair ride sequence that's not only poetically euphoric but also makes brilliant use (no kidding) of the Buggles's "Video Killed the Radio Star".

Yet there's a hard core of realism in Sarah Polley's script and direction. The lure of infidelity, a friend tells Margot, is about the thrill of the new; Polley then cuts from three youngish women naked in a shower to three much older women, to show that flesh, and dreams, lose their sheen.

Actor turned director Polley based her acclaimed debut Away From Her on a story by Alice Munro. This follow-up also shows the influence of the Canadian school of finely crafted emotional narrative, embodied by Munro and Carol Shields. If Take This Waltz strikes us as uncomfortably literary, it's partly because we're unused to seeing films that address the private life in a thoughtful, complex manner.

Still, there's something uncomfortable about the dialogue in what's very much a thinking-aloud, these-are-my-feelings film. Margot cuddles up to Lou in the kitchen, but it's not the best moment for him, as he's slaving over a hot fricassee; she pulls back, aggrieved: "Do you know how much courage it takes to seduce you?" Take This Waltz is the sort of film that elicits the complaint, "But no one talks like that in real life." But really, it's a question of whether the film can persuasively make these people talk like that in this fiction – and for my money, Polley doesn't succeed.

In Blue Valentine, Michelle Williams superbly conveyed the everyday stresses and yearnings within a relationship, and she's just as fine here. Her oddly babyish features quiver mesmerisingly in a scene where Daniel tells Margot at length exactly what he'd like to do with her, and the tension between her gaucheness and her full-on adult desire is nicely modulated. Luke Kirby is good too, in a rather one-dimensional role. As for Rogen, he comes into his own in a cleverly conceived scene where Lou and Margot finally talk things through: except that we see and hear only what he says, his dialogue edited in jump cuts.

Despite the terrific acting, I wanted to slap all these smug, self-absorbed people. The only person whose spleen I didn't want to grind, is Sarah Silverman, mercifully gritty as Lou's recovering alcoholic sister.

Take This Waltz is, I'll admit, fundamentally not my kind of film, but I suspect it'll be many people's kind of film, in a big way – and I can't help admiring it. At the very least, it proves two things – that Sarah Polley is no mean director, and that rickshaw guys have all the pulling power.

Critic's choice

Get up close and personal (and political) with an artist, dissident and international hero in the documentary Ai Weiwei: Never Sorry. Meanwhile at the BFI Southbank in London, The Lodger: A Story of the London Fog is just one of the delights in the Alfred Hitchcock season which continues until 19 October.