Essential XML is hands-down my favorite, yet it got blasted on Amazon
I've already commented here that I liked this book. Too many technical books just describe the surface of their subjects, not much more than glorified how-to manuals. I prefer books which explore the concepts behind the subject. Essential XML is one of those books.
Two questions come to mind: why the big delay in publishing Essential .NET, and what is the next book going to be about?