Generally I write reviews only to correct (in my opinion) reviews which are off target. So, don't buy the Kindel version. Do buy the print version.
The term "Child Themes" is very misleading in WordPress. Hedegren's "Beyond the Blog" says, "If child themes are in wp-content/themes/ just like ordinary themes, then how do you use them and what do you need? Basically, all you need is a style.css file to tell WordPress that it is a theme, and in fact a child theme, as well as point to the mother theme. Whenever a template file is called for, WordPress will look for it within the child theme, and if it isn't there, it'll load up the one in the original mother template theme. The lingo may be a bit hard to follow, by the way, because the community really hasn't decided on what to call this relationship between themes yet."
Ok. So what did that say. It said, the benefit of Child Themes is the functionality of the template. WordPress looks for functionality in the Child first and if it does not find it there it resorts back to the Parent theme.(At least in my brain, it would be better to call it 'Child Functionality' instead of Theme. I think of the Theme as the skin). But this is the essence of the problem. You need the CSS, you need the HTML, and you need the Theme functionality. If you don't know how the Theme functionality works, then that is why you buy this book.
The book, "Making WordPress Beautiful" essentially starts with that paragraph and tells you how to build your own themes. You begin with Twenty Ten and grok the details until you are ready to build your own themes. (Really, your own templates with template tags.) And the book does it very, very well. Saving countless hours of downloading code, making flow diagrams, and in general staying in front of a computer for a week figuring out your own strategy.
Just buy the book. Save some time. However don't expect magic.I've already invested about 3 weeks reading the book. Of course I am reading other books at the same time and keep coming back. But it is an investment of time. Set up a MAMP, WAMP or LAMP development environment. And do multiple blogs for clients without colliding all of your projects together. (The book tells you how to set up a MAMP or a WAMP development environment on the localhost.) The first three chapters are the hard read. At different points, little light bulbs go off in your head. I will say, at some point (at least for me) the romance with WordPress ends. It is just programming with PHP template tags. But the payoff is competence with the subject and the confidence that comes therein to use WordPress as a CMS for lots of projects.
Thord, provides excellent resources on his site and at Wylie to complement the book. The only other resource that I would suggest is the excellent video by Chris Coyier (the CSS-tricks Chris Coyier). His WordPress video on Lynda provides an alternative view of the subject. I have found that I need both resources to stretch my mind around the subject.
So finale warning. "Beyond the Blog" is not a beginner book. And this book, "WordPress Themes" is the book that you read after you understand the importance of the "Child Themes" paragraph in "Beyond the Blog". If you are at the right stage in your WordPress career (building multiple WordPress sites), both book together form the cannonical book for WordPress that you have at your desk.
I would also like to say, that the layout of the book, quality of typography and depth of writing are refreshingly appreciated. This is a quality book.