The new film about the musician Nick Cave, 20,000 Days on Earth, is an interesting experiment in biography. I would say it’s not a completely successful experiment, but I’m in the minority (it’s sitting at 94% positive reviews on Rotten Tomatoes), and this is despite my long passion for Cave and my interest in biography.

The film depicts a staged, somewhat surreal day in the life of Nick Cave – his 20,000th day. It’s an inspired concept, and gives an opportunity to offer a film which sits between a behind-the-scenes documentary and a ‘This-Is-Your-Life’ concept. The ‘This-Is-Your-Life’ aspect emerges in a couple of ways. Firstly, two scenes with professionals forcing him to confront his past – one with a counsellor; the other with some archivists bringing out photos and objects from his past. Secondly, several figures from his present and past appear in his car and he talks to them. I wish the surreal aspects of this were pushed further. Both are interesting ways to convey some of the story of Cave’s life amidst the somewhat banal tasks of the everyday life of a musician, tapping away at a typewriter and a piano.

There are three scenes in the film which show its potential, scenes in which the film comes fully alive. The first is the opening credits, as a counter runs through 20,000 days of life with a fascinating montage representing the different phases of Cave’s life, evoking the sense of a life flashing before our eyes. The second is about three-quarters through the film when Cave’s first meeting with his present wife, Suzie, is ‘dramatised’. The ‘dramatisation’ uses the visual prop of a reel-to-reel recording of Cave telling of his erotic awakening at seeing her; the reel-to-reel is taken over by a montage of the women Cave is talking about, all the women he’s ever lusted after. The scene has an energy much of the film lacks. The third is the finale, as the day is capped with a concert. As Cave sings about how he’s evolving, transforming, the present day footage is intercut with footage from other concerts throughout his career, and the moves, the charisma, the presence, even if it’s changing, is the same. It’s a beautiful depiction of change and constancy in the life of one person.

What then do I have to criticise? The film idles too long over rehearsal scenes and conversations which, if scripted, are particularly uninteresting. At his best, Cave is poetic and insightful, but at his worst, he is insufferably self-important – and both are in evidence in this film in the sermonising monologues and the conversations. There’s also some critical issues about biography. The film explores a few points of Cave’s life, and it couldn’t, of course, have hoped to explore all of his long and extreme life. But it tends to anecdotise, without pushing him where it needs to. Anita Lane is given three seconds in all, appearing in a photo, the woman who Cave became involved with in high-school and was his muse, on and off, for a couple of decades. Then there’s Mick Harvey, who also gets less than a minute; Harvey was Cave’s right hand man from high school until a couple of years ago. When he left the band, he said cutting things about the performances having lost all edge and no longer pushing any boundaries. Yet all we hear about in the documentary is what a genius Cave is, and how he shines on the stage.

And this is indeed the central problem: either the film-makers have allowed Cave to shape this film so much it has become autobiography, and an unself-aware one, or it is a hagiography, an ode to his genius – probably both.