There aren't that many books on the QGD -- Marovic and Polugayevsky are the only authors that come to mind off the top of my head, and they're both somewhat dated. So there's definitely a niche for a book on the subject. The book under review is a godsend for a 1.d4 player like myself who wants a clear explanation of ideas. For instance, in the classical set-up (...c6, ...Nbd7, ...Be7), what does one aim for in the tabiya position that arises after 12....e5?The book, as the author makes clear, doesn't cover every main line: it restricts itself to the Tartakower, the Lasker, the Exchange, the Classical, the Cambridge Springs, and the Bf4 lines. The author explains the ideas in each of these lines using games from both past and present. Every class player who plays or encounters the QGD will benefit from this, and even experts may pick up a few things.In my humble opinion, mastery of QGD and QGA postions is essential for every chessplayer, regardless of whether he plays them or not.To this extent, the book belongs on every player's shelf.