Second Edition (June 2001) of this book is very good, and is - at the time of writing - the only DHTML book I've seen which teaches you W3C standard DOM based Dynamic HTML. This is a very important point in my opinion, and it really makes it the one and only book to choose until other books gets updated or new titles emerges. W3C standard based DHTML are supported by browsers like Internet Explorer 5+, Netscape 6+, Opera 4+, Konqueror 2.1+, Mozilla and other Mozilla/Gecko-based browsers, and is _the_ standard "all" browser will support in the future. But the IE4 and NS4.x browsers are not forgotten, the book teaches you how to make your code compatible with these browsers too, even though they don't support the W3C standard DOM.
The book has support and bug-information about various Netscape and Microsoft browser versions, but do not go into deeper details with the alternative browsers like Opera and Konqueror. Actually Opera is the only "alternative" browser which is briefly mentioned in the book. However the coding style used in the book always favours "feature sensing" over "browser sensing" when ever possible, so most code should work with the lesser known W3C DOM compliant browsers too.
The book is split into two parts, a CSS-part and a DHTML-part. It seems like a wise idea to teach CSS before starting DHTML, since most people starting on DHTML problably haven't used CSS that much yet.
It is a beginners guide, not an advanced book. The style is typical of the "Visual Quickstart Guide". This means the book is designed to be a combined reference and a teaching-book. In my opinion the book can be a little boring reading from start to the end, because it has a tendensy to repeat things. For example when you have learned the basic CSS syntax for defining styles you don't really have to get it spelled out how the syntax is for every style-property in the rest of the book. Just mentioning the name of the property and the possible values should be enough, and you can always check the code-examples if in dought. This is problably a matter of taste, but it is the reason I can "only" give this generally very good book 4 stars.