I think this needs to come with a caveat: the picture on the cover might lead you to think that it’s about subtle effects used to accent colour and give shape, detail and texture to your painting. It isn’t. For the most part, the paintings, and especially the demonstrations, use large brushstrokes and a semi-impasto style that doesn’t always suit the subject and, in several cases, leads to flat results.
All of this is a shame, because the author tackles a good variety of subjects from landscapes and seascapes to animals and portraits in oils and acrylics and this could have been an invaluable guide to the different techniques of application for each of them. What you actually get is a one-size-fits-all that misses as often as it hits.
Books on brushwork are relatively few and far between, so this is certainly worth a look in spite of my rather heavy reservations and you might find that, on closer examination, you disagree with me completely and that the approach suits you down to the ground. I’d be wary of buying it without having had it in your hands, though.