I just finished reading Brown's book, and found it fascinating for a number of reasons. She kept a detailed journal all the years she was with Cunningham, and wrote extensively to her mother, a dancer and therefore a knowledgeable and interested correspondent, who kept all the letters. She quotes extensively from these, so much of what is in the book is what she thought and felt at the time it was occurring.
It is full of profiles of the most amazing collection of people: Robert Rauschenberg, Jasper Johns, Peggy Guggenheim, Pierre Boulez, Marcel Duchamp, and of course John Cage, whom she loved, and Merce himself with whom she had a very complicated, and to me surprising relationship. For young dancers today, it will give a realistic sense of what it was like to be a pioneer in a very exciting period of dance in this country.