Joe Pass was one of the greatest guitarists who ever lived! So when he talks, one should listen.
This short book displays many of the chord forms that Pass would use in his improvised sections of his work. He had developed as system of “grips” that allowed him to improvise chordal progressions on the spot. Many of the chords are useful, for this type of playing, and his fans will welcome the opportunity to learn them. However, for more contemporary music and/or fusion, these chords aren’t as useful. You can take what works for you and use it in your playing without the need to memorize his whole system… unless of course, you want to!
It’s not a bad book, but he wrote other books that contained better material than this.