This book contains the blues patterns found in Jamming the Blues vol 1. However, it only contains the chord, presented in chord diagrams placed over the music staff. There isn't any music theories. It DOES NOT contain the actual comping patterns played while soloing in Jamming the blues, just the chords.
I really don't see any other purpose for this book except to present chord voicing. In the Jamming the Blues volume 1 book, the chord symbols are presented but not the chord voicing. Thus, this is where this book becomes useful. therefore, if you are not familiar with reading chord symbols, then this book will guide you, to some degree, with applying what chords shapes to use. However, if you know what a 7th, minor 7th and a minor 7th b5 chords looks like, then this book isn't necessary.