Although many of the web usability observations presented in the book will be helpful to web and ecommerce designers, the authors really could have said much, much more using far less space. Follow Steve Krug's style: be concise! The book under delivers in the sense that much has been left out which was researched but was not adequately covered in the book, such as usability issues as they pertain to ecommerce sites. Many, many pages were spent going into minute detail on how a particular user utilized a given web site rather than summarizing and following with concise conclusions, making the book onerous to get through. Irrelevant topics were also covered, such as web users' attention paid to dog's crotches (I kid you not, this is an actual topic, covered in depth), making it difficult to take the book seriously and compromising the authors' credibility.
In addition, the writing style was a bit immature. The impression I received from their writing was that of a group of undergrads who were given money and let loose in Manhattan and required to produce a paper to account for their efforts.
I had really looked forward to this book, and unfortunately it fell far short of my expectations. Although, there is a lot of good usability information in the book, I would not recommend the book on that basis, because the information must be ferreted out from all the excess prose.