I purchased the e-version of the book.The content is really good. If you want to learn music theory that is guitar based, this is a good choice. The CAGED system is outlined well. Good song references to help you make the connection that most other theory books leave out. For the price it is well worth it.My only beef is that the e-version is set up for 9"x12" format which is not print friendly. Printing on "normal" paper leaves out page numbers and some important footnotes.Desi, Fix that!