I have no idea just what the one reviewer thought that he "knew to be the truth" about ADSL, or where he learned it -- but the technical information in the book seemed to be both accurate and relevant -- from the context of comparison with other ADSL technical references -- Chen, Rauschmayer, ADSL Forum, and ANSI and ITU-T specifications. It contains less information about the ADSL trasmission protocol than Chen or Rauschmayer but much more than Goralski and presents a greater breadth than Rauschmayer. It IS, however, a technical book rather than a marketing book and, therefore, does not cover the political aspects or business applications in great depth.
The book does have a problem, however, in that the chapters dealing with the physical layer make assumptions about the readers background. If the reader is familiar with digital transmission framing architectures, the chapter on ADSL presents a well-written and organized summary of ADSL-specific physical layer attributes. Without this background, the material can become very confusing. For example, he talks about the ADSL control channel commands without really explaining what a control channel is. In an apparent attempt to avoid the mathematical formulas needed, the distinction between QAM and CAP is blurred somewhat. If this ranking system had 1/2 stars, I would deduct a half star for this.
It is too bad that the one reviewer did not bother to read the rest of the book -- ADSL is of very little practical use without the surrounding protocols and applications -- and the physical layer will normally be handled transparently by the hardware anyway. I haven't read "Implementing ADSL" yet but,from the description, it also looks like a book that takes a system point of view of ADSL.
If this book ever does go to a second edition, I hope the assumptions are better eliminated and specific products are added as examples.