If you are a guitarist who wants to build the fundamentals and knows how to read music (which you should know if you want to do things right), then this book is for you. On the other hand, if you are Joe Metalhead who wants to impress your friends with power chords, go somewhere else and quit reading the rest of this.
I have played guitar for 20 years. I took some private lessons years ago, which helped me to build the proper foundation. I also know how to read music. I hit the wall about a year ago and found that I hadn't really learned scales the way I should. This book and others from Berklee have fixed that. Of course, it has taken work but EFFORT = RESULTS. Much of what is out there is like the crumbs that fall from the table compared to this book and others like it from Berklee.
One caution... as a prerequisite, you should be familiar with the scale patterns as taught in Modern Method volumes 1-3. If you are not, you will have trouble finding the proper fingering for some of the pieces of music.
If you really want to know the guitar and advance, spend the $15 or so for this book. You will never regret it!