This book is an indispensible resource if you've already decided HOW to implement CSS on your site and are looking for the best explanations of CSS selectors and syntax. The sections on typography and block-level elements, in particular, are detailed and extremely helpful (all that typography was much more than I needed to know, but it's good that it's there).
However, do NOT use this book if you haven't decided yet which CSS methods to use and cross-browser compatibility matters to you (or your clients). Each chapter cheerfully explains CSS features the way the creators WISH they would work, without indicating serious bugs or pitfalls you may encounter in the real world when trying to implement them the way they tell you to. The browser support charts are buried in the back -- they barely scratch the surface, especially where Netscape 4.x is concerned.
Making design decisions based on the information in this book could lead to some very unexpected and ugly results. Instead, use O'Reilly's "Cascading Style Sheets: A Definitive Guide", which documents browser compliance much more thoroughly, and turn back to this book as a quick-reference while you code.