That book is a reminder of a time when Wrox & friends weren't trying to crank out 5 lb tomes on .NET SOAP Interoperability. So many modern books read like a student trying to pad out a page count for a professor.
I wonder what will happen to books like this, as these guys pass away. For instance, I don't see updated versions of Stevens' books, which are classics in their own right with regards to network and systems programming on Unix. I learned a ton of things from those, and wow, they're sure beautiful books.
We can hope that they might receive similar treatment as John Ousterhout's "Tcl and the Tk Toolkit" did. JOs work (including TatTT) is often held up as excellent writing as well. The second ed. of that book was updated by a group of experts w/ JOs blessing, but w/o his participation if I understand correctly. Indeed @davidw was a contributor to that project ;) (thx. david.)