The book does not claim to be an in-depth resource. The general purpose of the QuickStart series of books is to provide an overview of the main concepts and practices in use by web developers today. It is meant to be a STARTING POINT to introduce novices to technologies, not an in-depth reference. The authors of this and other QuickStart books point this out continually, yet still get bad reviews from people who have not taken the time to read about the purposes of various series from technical publishers. This is unfortunate for the public as well as unfair to the authors.
A previous reviewer mentioned what he took to be atrocious coverage of Ajax. The book contains two chapters exclusively covering Ajax. The first covers the fundamental techniques used to take advantage of this combination of technologies. The second chapter explores some of the popular Ajax toolkits currently available. This is consistent with the purpose of the book. Some readers may be interested in heading down the development path, yet others may be more interested in design and in using pre-existing tools. This book caters to both and has no intention of deceiving either reader.
The following quote is a good example of this. It is an excerpt from the title page of Chapter 16, which follows the introductory chapter (basic XMLHttpRequest usage, etc.) and precedes the Ajax toolkit chapter:
As for the dual-column formatting that some reviewers disliked, it is consistent with the formatting of the entire QuickStart series, as well as the QuickPro series of the same publisher. The format is nice for tackling specific techniques in a concise amount of space. It is not as abstractly engaging as conventional technical books, but it is not meant to be. The format is excellent for explaining techniques (especial design techniques) as well as for conveying a sense of quick forward momentum.
I've only recently started reading books from Peachpit Press. I like these books because they get me up to speed quickly, and act as a comprehensive starting point, allowing me to understand "where I need to go from here."