I gave my goddaughter Sophie a copy of this book for Christmas, and simultaneously bought one for myself. We're going to learn the QGD together. This should be interesting... I have played the White side a few times, generally starting with 1. Nf3, but I have next to no experience as Black. When I played seriously back in the 70s and 80s, my main Black defense to 1. d4 was the Grunfeld, and I sometimes played the King's Indian. These days, when playing quick games on ICC, I have gravitated towards 1... d6 and 1... g6, which don't require you to know much theory. But all that is going to change :)
Sadler's book is highly regarded, and I can see why. It's well organized, with a nice Q&A style of exposition that should make it accessible to lower-rated players. The analysis however looks fairly deep, and hopefully will give me sufficient depth of preparation for my opponents on ICC, who are typically 2250-2450. I will report later on its suitability both for Sophie and for me!