I'll have to work through a bit more to give a decent "appraisal" 
Just as an overview though, here's the stuff the book covers:
Book I
Improvisation
Cymbal rhythms
Interaction of parts
Meter within meter
Song form
Rhythm section
Clave: a universal rhythm
Phrasing: think like a horn
Muscular tension
Body motion
Book II
Ways of practice
Performance patterns
Book III
Ways of practice
Performance patterns
In total, about 120 pages of stuff