Before I bought this book I was hopeless at drawing portraits. I had been drawing for many years - mainly landscapes and observation drawings - but I had never drawn many portraits and the ones I had done were not that good. However, once I purchased this book, there was a vast improvement.
Giovanni looks at the major features of the face: the eyes, nose, mouth and ears. For each feature, he gives a brief description of the factors to take into account when drawing them, a step-by-step guide to drawing them and several example drawings. After explaining the techniques taken through drawing each feature, Giovanni takes a step-by-step approach to drawing the whole face and follows with several example portraits explaining the distinguishable features of each portrait. The approach goes through the basic steps to drawing the face from drawing a brief outline, identifying the major features and slowly building up the detail.
There are two things that I didn't like about this book, mind you. The first is that Giovanni doesn't explain about drawing the hair. All the example portraits have hair but I find they are drawn in a very simple and somewhat childlike manner. The second problem with this book is that Giovanni only shows you how to draw the features from one perspective. He doesn't explain about different expressions and only explains a bit about viewing the features from different angles.
I have used this book strictly as an introduction to drawing portraits. If you would like a more detailed book, I seriously recommend 'The Artist's Complete Guide to Drawing the Head' by William Maughan.
Overall, this is a good book if you are interested in starting to learn how to draw portraits; however people who already have experience may not find it as useful.