I just read this book, written by Greg Lawrence (he collaborated w/ his g.f. Gelsey Kirkland on the memorable "Dancing on My Grave"). it's quite long, stylistically what you'd call "chatty" -- the product of a prodigious number of rather revealing interviews w/ those who knew Robbins, often shoehorned into the text w/out much editing or interpretation on the part of Lawrence.
as a piece of prose it may be deficient, but thought of as a chronologically-arranged series of interviews (a la Peter Manso's "Mailer" or George Plimpton's "Edie") it's very interesting. Lawrence got many, many people to talk, and it's a good -- if not entirely thoughtful -- read.
how does Robbins emerge? in fact, he doesn't. we get a picture of a nasty, tortured, brutal man who was capable of stunning acts of kindness; a man who had sadistic quirks of personality but appears to have been the only person on earth to awe Balanchine; a man who loved kids and dogs, but not himself.
p.s., it contains some more texture to the ongoing "Did Balanchine want Martins to succeed him?" controversy. the answer appears to be no. (see p.450-55) NYCB manager Betty Cage is quoted calling the Board "stupid" and the chairman "dumb", picking Martins before G.B.'s death basically because he looked the part.
another great quote (from Wilma Curly), regarding G.B.: "George hated the school [s.A.B.]. He wouldn't go there. And every time I hear the quote, 'First a school,' I want to throw up. He hated the school."