Like so many, I was looking forward to reading this book--so much was promised by the pre-release publicity. Alas, I was disappointed. The book's thesis, that caste explains race in America, is not proven, in part because the author appears to not have a very good grasp of what caste is. When discussing American "caste," she stays with white (dominant caste) and black (subordinate caste)--but there is no such thing as a two-layered caste system--such systems have multiple layers with complex rules and interactions. A better analysis of American caste would show the multiple layers of caste within the white community AND those within the black community. Even then, seeing American racism through the lense of "caste" is not likely to be illuminating.
Also, I found the book poorly organized, the prose style rather mediocre, and the research rather shallow. There are many many books available that do a much better job of analyzing race in America.