As a dancer, Rudolf Nureyev was certainly a phenomenon. Born in 1938, he grew up in the central Asian Soviet republic of Bashkiria. He started intensive ballet training in Leningrad at the late age of 17 and became instantly notorious on stage and off three years later after joining the city’s Kirov Ballet, then the world’s finest classical ballet company. He defected in Paris in 1961, becoming not only a highly influential balletic idol in the West, but an icon synonymous with the art form itself, to a degree comparable only to Anna Pavlova’s fame earlier in the century. As a human being he was funny, intelligent, intellectually curious, and frequently sensitive, but also outlandishly narcissistic, as well as cruel, violent, and ruthless. We never quite understand him in Julie Kavanagh’s “Nureyev: The Life” (Pantheon, 745 pages, $37.50) but she preserves the complexity of his humanity without whitewashing him.

The London-based Ms. Kavanagh employs the British biographical method of treating direct quotes as units of one single continuous pipe laid down from the beginning of the book to its conclusion. Too often, however, she goes overboard, letting other famous names and Nureyev’s intimates rattle on aimlessly. In addition, she adopts the disconcerting practice of frequently not identifying who is speaking, saving that essential information for the footnotes. This is a mistake, undermining our engagement with what is being chronicled. When reading a biography, one certainly wants to know whether Stalin or Churchill — or their balletic equivalents — is speaking, so that one can decide how to weigh what they are saying. This tactic certainly diminishes the book’s readability, but after a while you just give up and acquiesce. Long and padded as the book is, the pace of the writing keeps it moving along rapidly. Sometimes there is a real quality to Ms. Kavanagh’s writing, as in her account of Nureyev’s defection, where you almost feel your own pulse racing along with Nureyev’s and everyone else who was privy to that cataclysmic event.

When it comes to ballet, Ms. Kavanagh is decidedly Anglophile, and her treatment of Nureyev‘s career prior to his arrival in England is disappointing. Her chapters on Nureyev’s years in Leningrad are insufficient, and these were the years that stamped his aesthetic definitively. Too often she seems to be submitting to his own myth-making accounts. Ms. Kavanagh does accurately chart his self-invention as a unique, androgynous, and in some ways revolutionary presence on the Kirov stage, but only by shearing away qualifying nuance about his male colleagues, who are more or less reduced — unfairly — to one stereotyped cart-load of hunks.

Nureyev’s impersonation of Albrecht in “Giselle” was undoubtedly unusual, but to write that when Nureyev first danced Albrecht, “the character ceased to be a supporting role,” as Ms. Kavanagh does, is ridiculous. Albrecht was the most noted role of former and future Kirov’s artistic director Konstantin Sergeyev, one of the most celebrated male dancers in the Soviet Union. (Ms. Kavanagh later contradicts herself, claiming that the role of aristocratic cad Albrecht had been retooled by the Soviets to become the dominant character in the ballet.)

Ms. Kavanagh is on surer and more familiar ground after Nureyev arrives in England in 1962. But throughout the book she unduly relies on citing the opinions of a few anointed critics, often leaving the reader with the impression that Ms. Kavanagh herself hasn’t really pondered long or deeply many of these aesthetic and cultural issues herself. She restricts her own in-depth analysis to perusing the surviving video evidence of his dancing, and she does this merely competently, for the most part meeting the needs of only the mainstream readership to whom the book is targeted.

Ms. Kavanagh does not at all shortchange the artistic side of Nureyev’s life, but the amount of text she devotes to his love life ultimately seems misspent. In Ms. Kavanagh’s account of Nureyev’s Leningrad years she is preoccupied with his romance with the East German ballet student Teja Kremke, and she is the first Nureyev biographer to have unearthed this relationship. Naturally, she wants to run with her scoop, but she writes at such length about the relationship that I couldn’t help feeling that she would have done well to have included one or two fewer paragraphs about Kremke and a few more lines describing the great ballerina Olga Moiseyeva, an important Kirov partner of Nureyev’s who is identified only as a “ballerina of [Ninel] Kurgapkina’s generation.” Nureyev’s anonymous sex partners must number in the hundreds, if not thousands. But after his long folie à deux with Danish danseur Erik Bruhn during the ’60s, Nureyev consciously decided not to get emotionally involved ever again. His subsequent relationships were perfunctory, even if sometimes protracted. And so the amount of attention that Ms. Kavanagh dedicates to the sulks, breakups, and reconciliations of these relationships that followed resulted makes one wish sometimes that she had simply stated, “Nureyev’s relationship with X was typically volatile.” Nureyev voraciously acquired jewels, houses, artwork, antiques, but was also infamously cheap. He consumed friends, lovers, employees, ballet companies, and his own body; his manic hunger to perform meant that he burned himself out quite early, though that didn’t stop him from performing the most demanding classical roles long after his performance had become cautionary admonitions. In 1990, he even forfeited the crowning position of his life directorship of the Paris Opera Ballet, to continue to spend months away from Paris performing. His admirers accorded him demi-god status, but one has to wonder if something as clinical as chemical instability was fueling his behavior. As for his existential drive and ruthlessness, I think they must be seen in part as a response to the fact that he starved as a child during World War II, as indeed had millions of Soviet children who were never given the opportunity to act out on a commensurate scale. The final 150 pages of “Nureyev The Life,” make for compelling reading. describing his embattled but fruitful tenure at the Paris Opera and the long, slow, inexorable incursion of AIDS, which finally vanquished him in 1993. As destructive as Nureyev could be, his decline registers quite properly and poignantly as the fall of a titan.

Mr. Lobenthal is the dance critic of The New York Sun.