I love this book, full of practical ideas. But notice they are not all about sketches. They are general art/drawing practicing ideas. I borrowed a copy of this book from a library and immediately decided that I need a copy of my own. That's how impressive this book is to me!
I am an art graduate and author but I am always looking for new books to encourage and progress my drawing. I really liked this book because it provided a range of easy to follow drawing exercises. You do not have to do them in order, and you can perhaps skip over those that aren't of interest. Practice in drawing is essential for anyone who wants to draw well - no matter your credentials, practice makes perfect and there are many exercises that can help here with that practice.
I especially like the tips in the first few pages from other artists and scattered throughout the book, as well as great website suggestions. Take your time to absorb and explore through this title - it is well worth the price.