Welcome to BalletTalk, Anna P.
We have a very extensive thread
here devoted to reviews and comments about Kavanagh's biography of Nureyev, as well as numerous other references to it in other of the forums. You can find these mentions by using the SEARCH button near the top of the page, toward the right side, but they may not give you the substance you seek.
As to
Baryshnikov at Work, 4mrdncr cites it in our Favorite Photos thread,
here, and again as a Favorite Book from Childhood
here, and innopac mentions it in relation to the on-line posting of the Balanchine catalogue,
here, but the book doesn't have a dedicated thread.
I have
Baryshnikov at Work, and it does have lovely photos. The text -- his feelings about some of his roles -- is geared more to the general reader than the ballet devotee, and I was disappointed by its superficiality.