I'm very surprised with this book. All the excercises aren't too demanding but, at some point, the author says that "all previous excercises shouldn't take more than 20 minutes of your time" and I thought "What?! no way!!, all previous drills took me twice that time!!.
It turns out that this is not a matter of "do this excersises" it is more like "if you can do all the excercises in 30 minutes or less...then you are a real player" and that's a real challenge. I've yet to finish the entire book in 30 minutes but i've seen the results, it does work, it made me faster, clearer and gave me a more powerful picking hand. It's really a great book.
But we have to put things in his real context. The book is old, very old, and doesn't show technics that are considered very important today suchs as sweep picking, bending or tapping and miss much of the most important scale shapes that are so common today. It also miss streching excercises (I did lost strech in my left hand while doing these excecises). Nonetheless, it will give a solid technic, the author is right, within six monts of practicing this book, you will start to sound like a pro.
What would I do if I have to choose between this book and - let's say - Troy Stetina's "Speed Mechanics..."?, well, I would buy this one and then, after I finished, I wolud pick up "Speed Mechanics...", mainly because after filiberto's book, Stetina's won't seen so frightening and I would really benefit from Stetina's.