The treatment of the use Fibonacci ratios in helping to identify market movements is very good. I have done a fair bit of back testing with the techniques and they seem to work fairly well. Not in all cases of course, the charts of some markets seem less disposed to the use of Fibonacci techniques than others. Horses for courses. Be prepared to work at it and spend plenty of time practicing it - I found it to be one of those reference books that you work and work and work in order to get the best from.
Concerning the last two chapters on 'Rythmic Wave Diagrams' and 'Harmonic Unity Within market Price and Time', be aware that the author isn't trying to teach any new techniques here, but rather floating some ideas. I'd say these last two chapters were 'interesting'.
Before you delve into the latter of the two you might be advised to brush up on how to add and subtract ratios, particularly in the context of music, and do some background reading on music theory to support what there is in this book. (I'd recommend the first twenty or so pages of 'Treatise in Harmony' by Jean-Plilippe Rameau' - an excellent book on the subject). Pay particular attention to the diagrams relating the octave to market charts. Go at it with an open mind, but question, question, and question again so that you're sure you understand what you're looking at.
All in all a good read, and, in my opinion, worth the money.