I have it find it useful occasionally. His videos are a lot better than his book IMO. He is an excellent teacher. A much better teacher than book writer. The book has so much information in it that it's difficult to digest at times. Ii's useful if I need to reference something I have forgotten. It might be good as a textbook if you started at the beginning and worked your way through it but GEESE, that's a lot of stuff to work through. It's worth the money. He just updated it to version 4.
I've had it for a few years and upgraded to version 3. Like ninworks says, it contains an undigestable amount if information...but it is all there! I use it as a reference and not necessarily as a curriculum. Absolutely worth the money.
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