I've just started reading this and so far it seems pretty decent. It's not really a strategy book, the focus is obviously on the mental aspects of players, namely the reader. Every strategy book I've looked at has recommended strategies for playing against a LAG player etc. What I've really enjoyed so far about this book is the systematic approach it lays out for classifying players, primarily yourself.
As the book points out, one of the hardest things to do is to examine one's self critically and without bias, this includes how you play poker. If you can be honest with yourself while reading this book and utilizing some of the questionaires you might be surprised at the results you find. Now, this may not be a critical point for upper echelon players because they've probably figured a lot of this out intuitively, but for those looking to get over-the-hump so to speak, this book may prove quite useful.
I'll post more after I've finished reading it.