Consider this. I bought this book (including the postage) for a total of £5.56. now if you consider that a single 1/2 hour guitar lesson will set you back upwards of £15 this is an absoloute bargain. I have been playing for over 20 years and have been a frequent dabbler. I've done this and that, but never found a way of bringing together what I understand about music.
What this book does, is bring those loose strands together and put them into 12 achieveable lessons. I am currently at about lesson 5 and have been amazed at how much I actually understand about scales, chord formations and key tones.
I would recommend that the reader have some basic understanding of the guitar before using this book, but it is not essential. If I were beginning I would look at something like Begin Guitar - by Douglas J Noble as this will give you the understanding of the easier open chords. This book focuses more on barre chords and sliding scales, which could be daunting for the beginner.
This book has already made me consolidate what I understand and has taught me a lot. I will definitely be purchasing the Fretboard Roadmap Rock book when I am done with this one. Highly recommended to all, especially intermediate player. This book will improve your playing!