In the front matter of this book Scott Reeves says, "This book evolved out of a need to organize my own practice materials and to develop a successful curriculum for my improvisation classes at ... the University of Southern Maine."  He identifies several valid approaches including practicing patterns and scales in all keys and tempos, transcribing solos of masters, learning the jazz repertoire, and playing with other musicians, making the observation that "every individual has to discover what approaches work best for him or her...." 

Each chapter has an explanation of how modes and chords are used in improvisation, various patterns and melodies that are to be practiced in all keys along with ear training exercises and improvisation concepts, a list of jazz compositions that use the mode discussed in that chapter, and a transcribed solo that demonstrates how that particular person (Armstrong, Coltrane, Rollins, etc) actually used the mode in their music.  There is a separate chapter for almost every mode or scale that one could imagine, including diminished whole step and half step scales, various pentatonic and blues scales, and all the modes. 

You will need to be able to read music to use this book and it is appropriate for players of transposing instruments. On page 1 of the first chapter, The Major Scale, he briefly describes the theory for building chords.  Then on page 2 he gives instructions for Improvising on Major 7th Chords and Major Scales:

1. Learn to play the basic chord progression on the piano.  Listen for the inherent "color" or mood of each chord, as well as the strength or weakness of the root movements.
2. Play the numbered exercises as written.  Listen carefully to the intervals and overall shape of the phrase.
3. Sing the exercise in all keys while mentally visualizing yourself playing it.
4. With the metronome clicking on beats 2 and 4, practice the exercise on your instrument, using your ear to transpose it to the other keys.  Start slowly and gradually increase your speed, keeping a record of your progress.  If you have difficulty with an exercise, slow it down, simplify it, or alternate playing with singing and visualization.
5. In the classroom, C, Bb, and Eb instruments may all play simultaneously by starting at the measures indicated in the chord progression.

He then gives a chord progression to be used with the exercises that in the first chapter is simply a major 7th chord played for four measures which then moves chromatically down in successive four measure blocks before repeating.  This is followed by specific scale exercises or patterns in the key of C for four measures that you are expected to transpose yourself on your instrument when the chord progression moves to the next key.

This is followed by a comprehensive list of jazz compositions that used the scale and instructions on how to use those compositions to improve your improvisation skills.  The chapter ends with a transcribed solo, in this case Louis Armstrong's solo on "Hotter Than That"  Most of the remaining chapters of the book follow a similar pattern.

If your goal is to become a master improvisor and you have the prerequisite theory and instrumental skills then this book is excellent and will provide you with inspiration to take your improvisation to the next level for years to come.  I originally acquired this book in the early 1990's and struggled to make any significant progress with it at the time but now find myself selecting excerpts from any chapter at random to explore some harmonic or melodic sonority that I haven't delved into in the past.  Keep in mind that you will need to have a good bit of prerequisite knowledge and skill to make the most of this book.