I'm an intermediate classical guitarist, and recently picked this book up to improve my technique and to strengthen my hands. On the first count, I can't really say it's been too successful yet, but then, I've only gone through the first few pages. HOWEVER, on the second count, I can definitely say that the exercises included in this book are *awesome* for developing strength in the left hand, and for gaining independence of the fingers on the left hand. I can really see and feel a difference in the solidity of my fingering after just a few weeks of doing the exercises. But man, oh man, do *not* open this book thinking that it's going to be a cake walk, because it isn't. The exercises are difficult, and they hurt and are frustrating at first. However, if you can stick to them, and are humble enough to accept the fact that your technique might just be weaker than you thought - then you will reap rewards from this book.
The book also contains Giuliani's entire 120 exercises for the right hand - having done these independently myself, I can attest that they are invaluable, and make a fine addition to this book.