This is a really good book in that it introduces a number of important positions, reviews them, and provide some suggested readings in the end of the chapter. It strikes me as exceptionally clear and well written.
Potential readers may be interested in that Kane himself is a (free will) libertarian. His program is to reconcile the libertarian view of free will with "what we know in modern science" (see chapter "free wil and modern science"). He has written extensively on free will and is an authority on the subject.
I am not a professional philosopher, so it is hard for me to put it into relation with the rest of the contemporary debate around free will. However, it strikes me that even for an analytic philosopher, there are very few references to continental philosophers (Sartre and Engels and their contemporary heirs have interesting things to say about free will, for instance). The exception is a short discussion about Nietzsche (only because another philosopher that Kane is discussing has quoted him). There are some links to Kant too, but where are the more contemporary continental philosophers? This is my only reason for not giving it 5 stars.