Reading this book I felt a bit like Mollière's Would-Be Gentleman relearning his vowels and consonants as though they were something new to him. Chinese is my life obsession, so I pretty much already knew most of the content of this book - but you can often pick up useful bits and pieces from more basic works, so I feel it was worthwhile. Also, I met the author many years ago at a conference, which is one of the reasons I got the book in the first place.
I think this book is best suited to high intermediate students - otherwise a lot of the information is bound to be a bit obscure. For example, I think it would take a good bit of background in phonetics to understand much of ch. 5 "Pronunciation". And some bits of information were repeated three or more times in the book. But overall this book is a good, more up-to-date addition to existing works on the Chinese language by e.g. Robert Ramsey, Jerry Norman, John DeFrancis, and many others.