Let us get a few provisos out of the way. Nobody who is not already some sort of enthusiast for Nick Cave – singer of Old Testament tales and chronicler of hungry crows – will have much time for this singular documentary from Iain Forsyth and Jane Pollard. It's not just that the film is about the Australian émigré and nothing but the Australian émigré; it's that no inviting avenues are opened up for the currently unconvinced.

We are allowed almost no moving footage of earlier incarnations of Cave. The Birthday Party, those incomparable Dadaist noise terrorists, are seen only in monochrome stills. None of the late 1990s tunes that unexpectedly widened his audience to the dinner-party set make it to the finished film.

This is a piece about Nick now. He potters about nicer corners of Brighton. He visits an analyst. He watches Scarface with his two boys. In a sequence that pushes into the deified area that lies beyond mere hagiography, we watch him select archival items for inclusion in a "Nick Cave memorial museum". The Egyptian pharaohs were treated less indulgently by those responsible for postmortem arrangements.

Yet for all the undeniable self-regard – we are very, very fond of ourselves – 20,000 Days on Earth remains an effective, occasionally moving piece of work. Forsyth and Pollard, long-term collaborators with Cave, have worked hard to concoct a visual and aural style that meshes with their subject's singular sensibility. Erik Wilson's lovely cinematography finds damp beauty in the Sussex skies. Kylie Minogue (fair enough) and Ray Winstone (why, exactly?) turn up to press Cave on the underpinnings of his art. As it progresses, Cave gradually allows weaknesses and vulnerabilities to show through. Mind you, we aren't ever allowed to catch sight of his bald patch.