I remember buying a previous edition many years ago and bought this one partly fearing that nothing new might have been added and that it might therefore be out-dated. I shouldn't have worried. There is plenty new in here and modern media are effectively covered as well as the more traditional oils, watercolour, tempera and gouache. It certainly is the sort of book which one can delve in and out of, either reading a chapter or section which is broadly of interest, or digging deeper into the detail of a specific issue. In my opinion the "materials" are handled more effectively than the "techniques", but perhaps I have this view because I find that the latter are better presented with good quality colour illustrations of which this book has none.
My one real criticism is with the manner in which the book is made. Yes it is a weighty tome, but I found it impossible to read without opening the pages wide open, which then immediately badly creases the spine. I haven't had a book which has "damaged" quite so easily as this for a long while and I am only surprised that thus far all the pages haven't fallen out. It's early days (!) but perhaps they won't and the apparent damage to the spine may be cosmetic rather than structual.
Nevertheless, it is a real classic and deserves a place on the bookshelf (or more likely the working desk)of anyone serious about learning the craft behind their art.