>Does the book cover mainly improvements in the interface, or does it also cover exploitation of the new application-related stuff like Web Services, SOAP, XMLUPDATEGRAMS, and those things documented as "for advanced programmers"?

There's an entire chapter on that stuff, as well as good coverage on the rest of the new features in 7.0. As far as I can tell from a light reading of the book, the authors didn't miss a thing.