I hate learning openings. This book has actually helped me learn the ideas behind the openings in a rather painless way. How can that be you may ask, since this is a book about the middlegame based on various pawn structures. Well, the reason is that you cannot really differentiate easily between an opening a middlegame and an endgame. They are all part of a seemless whole. Various openings lead to certain pawn structures which dictate certain middlegame plans for both sides. If you understand what the idea behing the middlegame plan is, then you understand the moves you need to make in the opening which makes memorization of variations easier. It also allows you to play the right move once your opponent goes "out of book" because you have a better understanding of what position the particular opening is trying to accomplish.
I'll give an example of how the book has helped me. About a month ago I decided to learn the Caro-Kann as black (mostly to cut down on the amount of theory I need to know against e4). So what I did was look through the various line of the Caro-Kann in the MCO and see what the final pawn structures looked like. As it turns out, there are only about 5 pawn structures that are likely to develop. They are the: Caro-Slav formation; Kingside pawn chain; the panov formation; isolani; and the orthodox exchange center. Each of these pawn formations are discussed in pawn structure chess (the first three each have their own chapter and the last two are both found in the chapter on the QGD and its descendants). After studying the general strategic ideas for both black and white arrising from each of these pawn formations, I went back and looked at the variations again. All of a sudden the ideas behind the opening made sense and the moves of the variations seemed logical because I knew what the purpose behind the move was (As Silman says, the real purpose behind the opening is to create an imbalance and then develop around that imbalance).
The effects of this book have helped me in the first game I played as black in the Caro. My opponent (rated over 100 pts higher than me) played a variation of the Caro that I wasn't familiar with. We both went "out of book" fairly early. However, I kept in mind what the middle game pawn structure was that I was aiming for and where my pieces needed to be to accomplish that goal. Well my first outing as black in the Caro was a success. The allegedly "dull" or "boring" Caro notched a 20-move win for me -- not bad.
This book has also helped me see the similarities between various openings and how one opening can transpose into another. This is critical information to have at your disposal. The book does not exhaustively treat any particular pawn structure, however that is not its intent. The idea is to familiarize the reader with the structures themselves, the openings that they are most likely to arise from and the strategic ideas for both sides. Certainly entire books have been written on the isolated pawn. But this book is a great starting point to give an overview buttressed with a few examples of each strategy either succeeding or failing.
All-in-all this is an excellent book. I really do not understand some of the criticisms I've read about it. The book is not supposed to be about pawn play so there is no comparison between it and "pawn power" because each book attempts to cover a different idea. Moreover, the fact that some of the examples are one-sided does not bother me because the idea was to show how a strategy is carried out in its pure form. The lack of depth of treatment of each structure is also the book's strength. The idea is to give an overview, not an exhaustive treatment since such a treatment could conceivably cover an entire book or more for each chapter (or subchapter) in the book. If you are serious about improving your understanding of how to conduct a middlegame and how that middlegame is tied to the opening due to pawn structure then this is the book for you.