What a totally brilliant book, and I even understand some of the first couple of chapters! Seriously, what with Karen's direction and this book I reckon in another 20 years I'll be improvising at 60 bpm - no sweat!
Mind you, only over a II V I progression in D major
At least it's a start.
On a more serious note, the book is very good and there are some really useful hints about using the cycle of Vths and modes and major scale harmony - and that in the first 50 pages.
It's quite an expensive book but well worth it.