As part of the renaissance in big screen documentary making, we have been blessed with some fine, music-related films. We've had 'Dig!', 'End of the Century: The Story of the Ramones' and now 'The Devil and Daniel Johnston', a study of one man's creativity and struggle.

Johnston became known to a mass audience when Kurt Cobain started wearing one of his t-shirts around 1992, but by that stage 10 years of his musical story had already passed. Born into a religious family in West Virginia, Johnston was creative from an early age and, as his mother says, only cared about "making art and being John Lennon." As a teenager, he got more and more consumed by music and art, but his eccentricities became troubling and, after dropping out of college, he was diagnosed with manic depression.

Having seemingly exhausted the patience of his family, Johnston left his brother's home and went to work with a carnival, ending up in Austin, Texas where his musical career began to blossom. He started releasing home recorded tapes of his music and worked his way into Austin's thriving music scene, later becoming the real star of an MTV programme on the city. But for every success in Johnston's life came a flipside and in the 20-plus years since his star turn on MTV, his ever-growing acclaim has corresponded with many harrowing times.

Winner of the Best Director award at the Sundance Film Festival, Feuerzeig uses the brilliant archive material Johnston himself shot from his teen years upwards to document his subject. The result is a funny, hopeful, heartbreaking and unsettling film whose audience shouldn't be limited to just music fans or devotees of Johnston's work.

Using interviews with family and friends, Feuerzeig paints a vivid picture of Johnston. What the film doesn't have - it must be said understandably - are recent interviews with Johnston himself. But the documentary is arguably all the more powerful without them. We see Johnston now as a withdrawn and chronically overweight middle-aged man, cared for by his elderly parents, but at the same time still playing shows and experiencing an increased interest in his work.

'The Devil and Daniel Johnston' is an important film - not just for what it says about self-empowerment and unfettered creativity but also for its examination of mental illness and our attitudes and feelings about it. Johnston's music has touched many; his story deserves to reach far, far more.

Harry Guerin