Without doubt the author is knowing what he is writing about. Unfortunately the book spends a lot of pages on how to install and configure the program and with mini references about the various parts. These mini references are too short to give an idea what the tool or filter really does and how it can be applied but they waste much more space than a short explanation should use.
The author uses terms that were not explained at this time and without reference to other chapters. He even uses physically wrong terms (f.e. in the infrared section). It seems that the author tries to cover a wide scope of handling photographs but therefor the depth and quality of the given information suffers. So most of the described procedures are handled in a cookbook style - only the "how do I do this" is handled and mostly never the "why". My presumption is that the author largely reused the lecture scripts of the courses he teaches.
The organisation of the book is somewhat chaotic. The same techniques/tools or little variations of techniques are explained in different sections of the book.
Overall it seems to be unclear what the target audience is - absolute beginners, photographers without computer knowledge or something else? I didn't get it.
Such an important thing like blending modes is handled on half of a page! Luminosity masks are not even handled in the book. Vibrancy handling in different color spaces - nothing.
I give two stars because of the printing quality with lots of images and because some of the tutorials in the book can be beneficial to absolute beginners. Every serious photographer should stay away from the book and try to get a copy of The GIMP.
by Carey Bunks even if this is over 14 years old.