I used this book as one of the main references to my university project. The book is a great way to jump in modelling/digital sculpting in Zbrush. If you're a beginner and wish to model a human, than this book is for you. Every step is described in details as well there is always an image, showing the step.
The only thing that I didn't follow was creating meshes ( body and head). The author used a sculpting approach to do that. Personally, I will recommend to create them in 3DS Max, Maya or Blender. Luckily, there are a lot resources and tutorials in the Internet. The reason is his approach, can be difficult for beginners and for people who haven't got great artistic skills.