This is a very comprehensive book, a reference book for anyone who wants to start managing a Drupal based website (version 6 and 7). I thought it did a very good job using concrete examples to explain various actions and methods to do various tasks a webmaster/administrator would need to know how to perform on such a site. I couldn't find anything missing, so this would be a very useful book to have on your desk, at least for the first few weeks/months of managing the site.
I've developed Drupal sites in the past so I was a bit underwhelmed by this book to begin with, most of it seemed redundant compared to my previous knowledge. Then I took another look from a very different perspective and decided that it was a very good book indeed.
The book is NOT intended for engineers or highly savvy power users, it is for users who need to manage a live Drupal site and need to get a comprehensive knowledge on how to do things in this platform as administrators / webmaster of a site, for people who possibly never managed a site before, especially not a Drupal based site.
The book goes through all the important aspects, beginning with the "What is Drupal?" part through brief explanation of CMS platforms in general, and then starts diving in, starting with the basic building blocks of a Drupal site - content types and units, through to understanding modules, blocks views and more.
Then chapters are divided by the different areas: content, looks, user management, etc. and each area/feature is explained by a concrete example scenario or two, and the how to content in relation to the scenario so a complete picture is given to the user.
The book goes much further than that and discusses several possible scenarios (ecommerce, multi-lingual, events) that can be handled by optional modules, how to set up the site to take advantage and manage the additional capabilities.
All in all a high-quality and useful book if you are the target audience, it won't teach you how to create a module or design a theme, but you might understand more what you need to ask a developer/designer to do for you in relation to Drupal.
Note that Drupal is approaching version 8 as I write this review, and although Drupal 6/7 might still have some years in which they will be relevant, the book may become outdated.