No-one shoots beautiful, ‘troubled’ people with great hair (in slow-motion, to electronica) quite like Xavier Dolan. For this and other affectations, the young Quebec auteur inspires devotion and derision in equal measure. Incredibly he’s only 23 years old, yet Laurence Anyways is his third feature and another Cannes prize-winner. The most exciting young filmmaker in the world today? Possibly. A great director? No, not yet, but this is a major step forward after Heartbeats.

Set in 1990s Montreal, this is a decade-long gender bending Almodovarian melodrama of identity confusion and doomed love. Laurence (Melvil Poupaud) and Fred (Suzanne Clément) are best friends, soul mates, lovers – only Laurence wants to become a woman, which naturally complicates things. But Fred can’t break away and it’s this decision to stay that eventually tests the boundaries of their love and the loyalty of their families and friends.

Dolan’s script doesn’t make it easy for Poupaud. Laurence can be callow, self-absorbed and – at times – an absolute arsehole.  Fortunately Poupaud (a fine actor who has worked with Francois Ozon) radiates charisma and vulnerability.  He also looks androgynously ace in a frock (like Robert Forster from The Go-Betweens when he used to wear dresses). Clément is even better. She has an animalistic ferocity and simply burns up the screen, most memorably in a café sequence where her simmering rage, confusion and depression finally explode. They are a brilliant, maddening couple and capture the crippling, obsessive nature of self-exploration and needy love. This is relationship as grand orchestration, amour fou at its most exhausting and exhilarating. Whether Dolan’s underworked narrative pulls off the delicate balancing act of exploring both Laurence’s sex-change odyssey and their relationship disintegration with its accompanying emotional and sexual complications is open to debate, but you have to admire the ambition.

Inevitably for a nearly three- hour movie there’s quite a bit that could go. I could definitely do without the screeching Felliniesque troupe of cabaret and burlesque queens Laurence befriends. Dolan also struggles to make the older characters, especially Laurence’s parents, anything more than paper caricatures. Understandably he’s a lot better at writing pathologically adolescent narcissists.

As you would expect from Dolan, Laurence Anyways is art directed up the wazoo. He  mixes up contemporary and retro music video tableau with youthful vigour and energy. The club scenes are a hot mess of shocking pinks and neon blues. And in a couple of explicit 80s homages, he really does give great euro-ponce.  It will be fantastically irritating if you aren’t attuned to the sensibility. If you are, various scenes will leave you swooning with delight. The stunning Fade to Grey sequence conveys perfectly the opulent misery that Fred finds herself in when she attempts a ‘normal’ life away from Laurence – much more fittingly than any of Dolan’s often overcooked dialogue.

Dolan doesn’t even try for specificity with the cuts, which are a jumble of 80s goth, synthpop and 90s French ballads. He isn’t just churning out jukebox imagery in place of narrative though. Well, maybe sometimes. At times Laurence and Fred live their lives like characters in a music video – scrawling poetry on each other’s bodies,  making up and breaking up within scenes – so in a way it makes perfect sense.

Clocking in at an absurdly (over)long 161 minutes, shot in academy ratio, wildly uneven and episodic and with at least three possible endings, Laurence Anyways is, like its hero(ine), a fabulous disaster. It’s alternately brilliant and dreadful, childish and mature, vapid and truthful. In the end it’s way too much but I loved it anyways.