What makes it so great? 
I looks like something I would put together.
Really. The inside cover is all the notes on the fret board. In the intro you learn foundational stuff. There is a scale chord chart in every key for both major and minor scale. Then a few strumming patterns.
There is both tab and sheet music of examples. It teaches you all the scale chords in C then there are practice progressions with strum marks on the staff. Next there is a scale and chord exercise kinda like hannon. This same structure is learned in G and other keys. On each page with thus structure you get picture charts.
Then you get the same structure in the minor keys. Scale, scale chords, practice progressions, scale and chord exercise. After this you learn basic blues chords with progression examples. All those sections are first position chording. Then you learn basic bar chords with progression examples and picture charts.
Next you learn moveable scales: major, minor,mixoludian, and blues. Then you have chord and scale exercises with each scale. The rest if the book contains more moveable simple extended chords with progression exercises. The book ends with several songs laid out in sheet/tab format.
I could translate this book into bass, keys and organ. If you can get through it you should be ready to play in service. It is so simple. It's a basic toolkit. It's rare to find really good books like this.
