This is not a particularly good biography, just an okay one. It will tell you who Bob Cousy is, what he did, what his basketball life was like, and what he did retiring as a player in 1963, but...something is lacking. Although author Bill Reynolds states that he interviewed Cousy extensively (between 2002 and 2003), the book absolutely feels based on secondary sources (it does use them, the notes say) and feels as though it only scratches the surface of Cousy's life and career.
One reason I feel unsatisfied is that about seven years ago, I read a book called The Killer Instinct, a book Cousy himself co-wrote in 1975 and which Bill Reynolds uses as a secondary source (and discusses in chapter 11 of Cousy). The Killer Instinct is Cousy's account of the psychological and moral problems his obsession with winning (driven by a fear of failure) caused him--extreme emotional reactions to losing games as a player, and temptations to cheat (by committing NCAA recruiting violations) as a college coach. It's a brooding book; it's also a more satisfying book, being more personal. If it were still in print, I'd recommend it instead of Cousy (or at least in addition to it) if you want a biography with more depth.
Often, Cousy simply runs out of interesting things to say about its nominal subject, and settles for telling tangential stories about the Celtics dynasty teams and even about the young NBA.