This is one of those rare works which does not care to have one eye for the wannabe market. Suitable for both technicians & those folk needing to see the "big picture" (e.g. Managers)
This book's focus is on performance and capacity of applications in the e-commerce infrastructure, and like the other books by the authors, it covers every facet while explaining the what's and why's. More importantly, this book will not overwhelm readers who are rusty in math because the authors weave in refresher material as they go along.
What makes this book valuable is the blend of business and technical topics, particularly in Part I where business models are thoroughly discussed. I personally believe that this material is as important as the more technically focused material in subsequent chapters because it wakes up the technical reader as to why their job of developing scalable solutions is important by linking the technical aspects to business imperatives.
Parts II (Evaluating E-Business Infrastructure and Services) and III (Capacity Planning for E-Business) are the heart of the technical matter, and the chapters systematically dissect each aspect of an e-commerce infrastructure from the application layer point of view. This is where quantitative methods are introduced and where the value of the spreadsheets on the CD ROM increase. Note that there are more up-to-date versions of these spreadsheets on the book's associated website, as well as errata for the book.
Practical considerations that blend the business and technical perspectives are presented in Part IV (Models of Specific E-Business Segments). This chapter consists of case studies that tie together all of the preceding material using real world examples.
Because this book is more focused on performance and capacity at the application and business model layer, you should read the authors' newest book, "Capacity Planning for Web Services: Metrics, Models, and Methods". That book covers the lower level details of the infrastructure
to round out the picture of an end-to-end view of performance and capacity management.