For most Cookbooks, you have to have a general idea or experience of the topic the book is about. The same is true here except what you need to know is how to navigate your way around a terminal, whether it by Putty for Windows or any terminal for Linux or Mac. If you know your way around a terminal window, then you'll be just fine with this book.
The book goes over the basics of everything on how to get your rPi setup. Ideally, you'll start off with it connected to a monitor and keyboard with a mouse and everything will go smoothly. After that, you can run "headless" if you would like by using ssh to do everything else assuming you have it connected to the your router or use a wireless USB dongle.
Once you get it setup, the book goes over in nice detail, how to work on the rPi. If you're familiar with Linux, you don't need to worry about Chapter 3. If not though, it's a nice little primer on how to work through the terminal.
The software section is fairly useful, although I haven't really used most of the stuff as I didn't really see a need for the software myself. If you want some of it yourself, it'll be useful.
The Python section was nice and gets you going but you'll want a more comprehensive book on Python if you're learning.
The last section on GPIO was okay and it was in an early release form and needs more work. I can't really say much about it since I don't have the hardware to interface with it yet but it looked useful.
As an unfinished book, I thought it was pretty good where everything was in a more polished form. There are parts that are missing towards the end of this portion and notes for the author himself but it's expected of an early release title. I look forward to the completed version.