There is too much emphasis throughout this book on how to fill out form fields that are fairly obvious, and yet the most important subject matter is oftentimes glossed over. For instance, the topic of conditional actions arguably deserves its own chapter, or at least an extended section — not one and a half pages up front, and then several paragraphs later. A few key e-commerce topics are absent. A glaring example of this is the lack of discussion of how to sell digital products in one's store, which nowadays is important enough to warrant its own chapter. Subscription services (typically with recurring payments) is another worthy topic completely skipped. These deficiencies may be due to the authors' focus on explaining the admin pages and settings found within the basic Ubercart modules, rather than a much more pragmatic approach of exploring the steps needed to reach a goal (e.g., selling downloadable files) regardless of what modules are utilized. Admittedly, Ubercart and all of its constituent modules comprise enough details and moving parts that could justify a book of greater length. Yet room could have been made for those details and advanced topics by spending less time describing (obvious) form fields. Lastly, if the authors had expected the reader to be able to follow their instructions throughout the book, they should have made it more clear as to which modules and options should be enabled at each step.
Books can provide a good overview of a topic, but it seems as if this particular book is somewhat lacking in that regard, preferring to explain the obvious. Also, the preceding paragraph implies that the book is poorly written and/or edited. Hence my question: Why prefer this to free tutorials and wikis?
I've noticed several design suggestions in your code.