If you agree with this quote, you oughta like this book: "Knowing the keys and scales for a song is important to being able to improvise a solo."

Clearly written and seems to have a constructively flexible attitude about making loose things (the blues, for example), match tight things (western music theory).

It's not really for me, but it was good to spend some time with it and be reminded about all the stuff I'm too lazy to (or dismissive of) learn.