I finally bought the book and found it very interesting especially the section with all the type of material or objects you can paint (ex: leather, clouds, skin, hair, trees, etc.)

In over all I love it. Still if you are an experienced artist, you could want to check elsewhere. But there are some project that are very detailed in the book. While other articles rapidly talks about the subject without getting into the details.

It's also not a book to learn how a software work but rather when you know how to use it but do not know what to do with it.