I bought this book in conjunction with Dreamweaver CS3 - CSS, AJAX, and PHP (5 stars by the way), all I can say is that it feels like I'm reading the help files rewritten in different words, with a few added details. It doesn't explain much, not much detail - sort of like, here is was this does, figure out the rest yourself.
100 essential techniques - I should have figured it out through its gimmicky title. There's no proper hierarchal way of organizing the information. It's like the author chose 100 random points and attempted to limit each point to 2-3 pages. Obviously some things can be explained in a paragraph, while other things require an entire chapter. Thus, the pages contain a lot of blank space. I'm really not sure if this book is targeted towards beginners or advanced users. Sometimes the author puts random/related ideas into the margins (I have yet to understand many of them).
All is not bad. Sometimes the book comes in handy when I need a quick reference for something. Recently, I needed to embed a flash file in my page, but forgot how, so I quickly looked it up, and the instructions were satisfying and straight to the point. Although, I suppose the help menu could have done the same. Do not try to use this text for explanations about Ajax or PHP; they're extremely primitive and useless.
Overall, I have mixed feelings about this book. What I like most about it, is that it reveals certain useful options that I would have never thought about, for instance, progressive downloading (for jpeg images) and interlacing downloading (for gifs) allows images to 'fade in' when they download into a browser, instead of appearing line by line. This simple little feature takes makes your site look way more professional and clean, who knew? It also reveals many 'best practices' for accomplishing certain tasks, which I think is extremely useful.