It is at least unsatisfactory that there are no new books in the main language, nor are there new editions of the books of Wagner and Madera. I read “Programming in Mathematica” 3 years ago only once, since I borrowed it for 2 weeks, but my pure impression was that I really needed this best expert book. Strictly to the question: it is not only useful for the WM8 user, but the more M-functionality is becoming more and more. I believe that this classic book should be read more, because it is a pure M-framework, not deals with the details of specific implementations, which today is even more important for such a comprehensive system.
His (R.Maeder's) is another "Computer Science with MATHEMATICA" is very good and almost 12 years old, but not aimed at the core M.
I find the Sal Mangano M Cookbook to be newer to the intermediate reader, its disadvantage is that it is a bit confused, and its style is not very convenient for a deeper understanding.
The third edition of Mathematica in action by C. Wagon is a really beautiful book, but more about Mathematica applications. Someone wrote about this, that every page was gold, and I am close to this opinion.
M. Trott's impressive 4-volume book was supposed to be updated with dynamic interactivity and other new features in versions 6+, but you can read August 2008 on its web page: although Mathematica Version 6 is released, GuideBooks update takes more time than predicted. Therefore, instead of having new versions in the summer of 2008, the expected date is in 2009. " There is still no new version.
Taking into account all the above, I believe that the book by Leonid Shifrin is very necessary for the Mathematica community, and I hope that there will be paper editions.
I found that in all M-books the chapters on pattern matching and rule-based programming are quite short, while the general opinion is that the full potential of Mathematica can only be used to master both functional and programmatic programming, and they are both worthy of a whole monograph.