Barney Hoskyns says that perhaps the "real essence" of Tom Waits is that he is "on one hand a man of great emotional warmth, on the other an artist fiercely protective not only of his private life but of the mystery of his own gifts". That assessment - as good as any you're likely to read and the perfect summation of this book - comes 428 pages into Hoskyns' 501-page biography. The author's greatest achievement here is that by page 428 you're still as interested in the things he has to say as when you started the first chapter.

As the 'A Life of Tom Waits' suggests, this is not an authorised biography and Hoskyns, who has also written books on Prince, James Dean and Ozzy Osbourne, failed to get access to some of the major supporting players in the Waits story. People would check with Waits and his wife and collaborator Kathleen Brennan if they could talk to Hoskyns; the author became accustomed to receiving the same response. While these snubs have upset Hoskyns - enough to pettily include transcripts of emails - he shouldn't dwell on them: he has talked to Waits enough times, met enough people who were willing to talk (and had something interesting to say) and done more than enough exhaustive research that this book on the journey from hopeful to icon will stand the test of time.

Those with no time for Waits' public persona and who find his interview hyperbole and ramblings tiresome will not be converted here. Those in thrall to all of the above will find no revelation that will force them to sell their collection. This is, as one of the declining interviewees put it, "a glowing tribute" - even those aggrieved at no longer having access to the Waits tent speak of him fondly and are only aggrieved because they enjoyed his company so much. It's the same with long-time devotee Hoskyns: million sales, you feel, wouldn't compare with having his work validated by the man himself.

The biggest disappointment of 'Lowside of the Road' is not as might be expected these missing interviewees but something which was in Hoskyns' control: his track-by-track analysis and descriptions of Waits' albums scream from the pages for tighter editing. It's one thing reading these sections when you're actually listening to the records, but outside of that context the bombardment of descriptions and references to other artists becomes irritating. It is, you might feel, a case of the fanboy coming to the fore and Hoskyns isn't helped by including a 'Top 40 Countdown' of Waits' best tracks as an appendix - leave that kind of stuff to monthly magazines, blogs and messageboards.

That aside, this is an excellent read and one which accomplishes an all-too-rare thing for biographies: makes you more interested in the work of its author as well as his subject.

Harry Guerin