Looking for something to fuel long-held desires to become an old-fashioned cock-out rock star? Then welcome Pete Townshend's emotionally wrought and self-flagellating autobiography. For here is everything you hoped was true: the ability to buy Ronnie Wood's house, a fresh brow-mopping girl in the hotel room, the television-through-window exuberance of bandmates, the close encounters with Mick Jagger's bulge.

But in Townshend's complex world there is much more too, perhaps enough to turn the rock dream sour: the awkward relationship with fans, the inability or unwillingness to recreate the hits of one's heyday with the Who (and the paranoid insecurity associated with that), the ordeal of sustaining a loving marriage, an unhinged childhood with an insatiable grandmother on the English coast. And at the end of it all is the auto-destruction, far more effective than his guitar smashing, an act that temporarily made Townshend one of the most reviled and misunderstood men in rock, which is saying something.

In many ways, this is an important book, a fearless account by an influential cultural figure from a period when rock music could still transform lives. The writer Nik Cohn was the first to nail the Who's significance, observing in 1971 that they had made themselves into both the epitome and the entirety of rock music. The best thing about them? They were disaffected and they were loud, and often with rock that's all you need. We may now judge them as a template, a renewable rebellion that has led  via the Clash  to Nirvana and beyond. And Townshend's chords resonate still: with Keith Moon and John Entwistle gone, he and Roger Daltrey still fly the flag defiantly at rousing live shows, something Townshend calls a "celebration machine".

But where Townshend can be an ungainly and a coruscating performer on stage, his writing is mostly the reverse; it is well-behaved and ordered, one catalogue of uppers and downers, mostly told at a flat pace. The book lacks the fiery eloquence of Townshend's windmilling mind, and there is a sad lack of hell-yeah enjoyment in his life, as found, for example, in Keith Richards's indulgent memoir. There are occasional flashes of irony, but too much straight-faced telling without showing, and an uncharacteristic lack of imagination in the architecture of the narrative.

But I did find myself laughing at the excesses, something Townshend also now finds absurd. In 1967, for example, he is worried that the Who are no longer the loudest group on Earth, surpassed in their ear-bleeding by (of all people) Vanilla Fudge. "They had found a way of amplifying a Hammond organ up to rock guitar decibels," he writes. "We were actually upset by this."

Townshend's story is essentially one of searching. His songs powerfully reference the act of seeking and the concept of the seer, and he has always been keen to engage his own followers with this spiritual quest. But it's a mission that has barely concluded at the volume's close.

The book is insightful about the creative process, haphazard and accidental as this often is; Tommy only makes sense to its creator once it has been performed live. I also enjoyed his memories of his time in the 1980s as an editor at Faber, an inspired shit-stirring exercise by chairman Matthew Evans and then head of fiction Robert McCrum (now of this parish), which managed the dual achievement of astonishing the old guard (PD James in particular was not impressed by his yobbo credentials), and bringing the fiercely old-school publishing house slightly closer to the modern world.

Townshend's biggest concepts were usually too advanced for both his bandmates and his fans, and the sections in the book devoted to the lesser ones  the Lifehouse, White City and Psychoderelict projects  suggest deeply ingrained psychological trauma in which the writer is struggling to get something off his chest.His explanation for the charges relating to his use of a credit card to access images of child sex abuse holds up to scrutiny and what those close to him know of his generous and charitable character. He has always been digging for clues to abuse in his childhood and was now actively campaigning for a way of helping others with early trauma, and fighting against internet companies profiting from indecent images. Banged to rights and rightly so, he appears permanently humbled by the whole ordeal, no longer defiantly above the law in rock god strides.

This is a worthwhile, comprehensive and culturally valuable account of a life, but its solidity is slightly enervating; it's no celebration machine. Unusually for me, it didn't inspire a rush to the iPod or Spotify, and it didn't leave me with the sense of elation I normally feel after brushes with the Who. In these sober and self-effacing times, Townshend gardens, sails, walks his dogs, loves his long-term companion Rachel Fuller, plans a new musical suite called Floss, and compiles definitive box sets. It may be unreasonable to continue to expect more from the man.

In 1967 Pete Townshend heard the voice of God. Confirming his reputation for working in mysterious ways, the deity chose to introduce himself to the Who guitarist at the Rolling Meadows, Illinois branch of Holiday Inn. "Suddenly it became clear that I longed for a transcendent connection with the universe itself, and with its maker," writes Townshend, adding, in a deadpan segue, that the band's drummer Keith Moon had other priorities on that tour. "While I made progress with my search for meaning, Keith was causing havoc with a birthday cake, a car, a swimming pool, a lamp and a young fan's bloody head."

The comical contrast explains what made the Who both one of the biggest bands in the world and one of the most restless. While Moon embraced rock stardom with open arms, Townshend wrestled with it, forever trying to justify himself to the spectre of the avant-garde artist and reliable family man he might have been. Townshend's years of psychotherapy ensure that Who I Am, which he first tried and failed to write in the mid-90s, isn't one of those rock memoirs that puts the what before the why. His past is a puzzle he is sweating to decipher. When a record label boss chides "Your fans don't know who you are any more," Townshend reflects: "Had they ever known? Even now I'm still trying to find out who I am." Or as the hero of the Who's Quadrophenia album has it: "Schizophrenic? I'm bleeding quadrophenic."

In Townshend's mind, the cataclysmic power of the Who's early work was rooted in trauma. At the age of six he was sent to live with his mentally ill grandmother, Denny, "a perfect wicked witch", who, he is convinced, allowed him to be sexually abused by her lovers; he also alludes to giving his mother's lover "the green light". The precise events elude him ("My memory just shut down") but the shards of detail are chilling: an unlocked flat, the "little Hitler moustache" on one male visitor, the beckoning of a car door. In one of disappointingly few insights into his songwriting, he retrospectively interprets his 1966 "mini-opera" medley "A Quick One, While He's Away" as a cryptic account of his time with Denny.

Townshend also believed that his music, informed by his art-school studies, reflected the damage done to a generation born amid post-war rubble and confronted, in adolescence, by the existential terror of the Cuban missile crisis. "As I raised the stuttering guitar above my head, I felt I was holding up the bloodied standard of endless centuries of mindless war." Most of his audience, one suspects, just enjoyed the noise and spectacle.

How many fans of the Who knew or cared that his ritual guitar-smashing was inspired by Gustav Metzger's theory of auto-destructive art? Or that the 1965 song "The Kids Are Alright" was partly informed by Purcell's Gordian Knot Untied? Call him pretentious  he does, happily, call himself that more than once  but it was this highbrow mission that propelled him towards the dizzying ambition of albums such as The Who Sell Out, Tommy and Who's Next. After a fruitless attempt to sell one grand concept to his bandmates he complained to his first wife, Karen: "It's like trying to explain atomic energy to a group of cavemen."

Townshend's unease with certain aspects of rock stardom may have pained him but it kept him relatively stable throughout the band's early years. Between 1967 and 1973 he steered the Who to greatness while spurning drugs and (most of the time) infidelity, and studying the teachings of the Indian mystic Meher Baba. Only later, as he confesses, did he become a cliché. On the Who's 1980 US tour he spent around $40,000 on cocaine and often fell asleep cradling a bottle of brandy. By the following year he was hanging out in New York crackhouses and conversing with the devil. "I was turning into Keith Moon." There were psychological shocks that might explain this downward spiral  Moon's death from a sedative overdose in 1978, or the 11 Who fans who were killed in a crush at a gig in Cincinnati a year later  but Townshend earns the reader's sympathy by refusing to ask for it. His prose is crisp, clear and unflinching.

Most rock memoirs run out of gas once the classic songs dry up and the major crises have been overcome, but Townshend's life after sobering up and splitting the Who in 1982 was never dull. He worked as an acquisitions editor for Faber and pursued several political causes in between sporadic reunions and solo albums. He also suffered from depression, briefly resumed drinking and saw his beleaguered marriage disintegrate. In 2003, he was arrested for accessing child pornography.

Townshend isn't coy about his sexuality. He says he is "probably bisexual", citing his attraction to Mick Jagger ("the only man I've ever seriously wanted to fuck") and a one-off liaison with the journalist Danny Fields. He describes his adulterous pursuit of several younger women in terms that often make him seem seedy and pathetic. But on this subject he is adamant that, as a victim of abuse, he was researching an exposé of the child porn industry. He is either a liar or the victim of a cruelly ironic misunderstanding. The evidence against him consists of a single unprocessed credit-card payment.

That cloud remains, but elsewhere there is sunlight. He has remarried, and his fractious relationship with Roger Daltrey has mellowed. Unlike Moon and the Who's bass-player John Entwistle, he has survived his addictions. He recalls singing the climactic line of "A Quick One, While He's Away"  "You are forgiven!"  while "thrashing at my guitar  frantically forgiving my mother, her lover, my grandmother, her lovers, and most of all myself". Without a guitar in his hands, reaching that cathartic moment proves rather more challenging, but Who I Am is an unusually frank and moving attempt.