Jonathan Williamson is established in the Blender community as an instructor for the Blender Cookie tutorial website. So it probably comes as no surprise that he should write an instructional book on using Blender. This one is an impressive work, and despite a relatively high price, may be worth your time if you want a thorough introduction to designing and modeling characters in Blender.
This book is intended to be the basis for an actual class in Blender, and it has several characteristics that make it good for that:
It starts right from the beginning and establishes a firm foundation before moving on
It is focused on a single project, with each section building on what went before
It doesn't overwhelm the reader with irrelevant information
These probably reflect the author's experience in teaching students directly. However, it does seem to be self-contained enough to be used for self-study at home.
This does make the book a bit less flashy than some others, and it doesn't cover absolutely everything. However, it does get to a very advanced level in Blender's modeling capabilities, including sculpting, normal maps, and retopologizing -- subjects I've seen very little of elsewhere. I find the uncluttered style to be engaging and easy to follow.
The book does not go very deep into animation or rigging, and it only gives a very brief introduction to lighting and (ordinary) texture mapping.
The book also comes with a DVD with supplementary video tutorials which cover the more advanced topics with a different example charcter, and Blender files for the examples in the book.
I'd like to add that if you have the "Blenderella" tutorial (by Angela Guenette) which follows a "polygon modeling" approach, the modeling technique used in this book ("box modeling") makes a nice contrast/complement. These are both popular techniques for making complex models -- essentially the difference between 'building up a surface' and 'sculpting a solid figure'.
Given the gentle way the book introduces Blender, and the amount of material it covers, I might very well recommend this as a first book for students or hobbyists who really want to learn Blender, although it would represent a serious commitment.
Terry Hancock is co-owner and technical officer of Anansi Spaceworks. Currently he is working on a free-culture animated series project about space development, called Lunatics as well helping out with the Morevna Project.