I picked this book up on a whim, and I was very pleased to read that someone had put together a book that contains much of my own philsophy of teaching voice. I'm only giving it 4 stars because the name-dropping throughout the book is irritating at best, and as some others have noted, his descriptions of what the vocal folds are doing during vibrato, etc. are not very scientific or accurate; however, the descriptions do help with visiualizations and it truly isn't necessary to know the science to learn to sing well.
Other things I like about the book are:
-connecting the speaking voice to the singing voice
-encouraging people to train their own ears by recording themselves
-exploring the middle voice
-the "do-it-yourself/imitation" approach; this works for many people
It's good that a CD is included; it really helps people hear the difference between doing it wrong and doing it right.
This is a good place to start if you want to learn to sing.