If you're looking for a reference, this is the book to get. The reference section is current VoiceXML 2.0 (October 2001), which is an advantage in and of itself. But the real strength of the reference section is its depth. Each element, (e.g., , , ) has an entry for syntax (how to invoke the element), a description (what the element is used for), a thorough discussion of its attributes (that is, a description of the attribute), a usage statement (the elements parents and children), and an example (a snipet of complete code that uses the element). The examples and discussion of attributes really set this book apart from its peers.
There is a brief discussion of the architecture of a VoiceXML app, and a couple of paragraphs discussing the differences between VoiceXML 1.0 and 2.0.
The book also gives, contrary to my expectations, a history of the voice industry, a history of VoiceXML, and a discussion of players in the industry. What makes this book's treatment of these topics unusual is that the authors (particularly Kunins, I suspect) actually know these fields. I don't normally want these sections in a reference book (it just adds bulk around the section I really want) but I found them quite compelling here. I learned quite a bit from reading them.
The book also contains sections on Dynamic VoiceXML, Security, Voice App Life Cycle, VUI Design, the Future of VoiceXML, and a case study. I haven't read these sections yet, so I can't comment on them. I do know, however, that the sections I have read are sufficiently superior to make this THE VoiceXML book on their own.
If I were to criticize the book, I would fault the authors' lavish praise of TellMe (this is minor and not unexpected) and the examples in the reference section. The examples are quite good for someone learning VoiceXML, and the authors are commended for including them. The fault (albeit a minor one) is that they are fairly vanilla. So, while I would have preferred more examples, I concede that such examples would make the book much larger and the inclusion of "advanced" examples to the exclusion of "canonical" examples would have made them less useful to developers learning VoiceXML.
Overall, if you are going to own one VoiceXML reference, THIS should be that one.
In short, this is the VoiceXML book I wish I had written. The authors have produced a comprehensive title that includes gems that could only have originated from masters of the craft.
My only complaint is that the book is a bit too biased towards Tellme (one of the authors is an employee), but this can be forgiven based on the quality and depth of the content.
My judgement is that this book is the most well rounded in-depth book on the topic that's been published to date. I am very happy with the mix of content, summaries of important concepts such as linguistics, speech recognition, and speech synthesis, as well as the in-your-face examples and complete reference. In fact, I liked it so much that I will probably be using it as a standard reference in my company's VoiceXML training course.
