Since I started drinking kombucha tea a few months ago, I've read several books on the subject. Now that I have read Gunther W. Frank's book, I don't feel the need to read any of the remaining others. He gives complete information about what's known about the culture, different ways to brew the tea, how to store the culture, what to do when problems arise, the effects of drinking the tea, etc. What I particularly like is that he provides all information he has come across, even when he disagrees with it. Unlike some other authors, he's not condescending or proprietary about kombucha.
He seems like a wise person. The final chapter, which is entitled something along the lines of: 'Is Health Really the Most Important Thing?' is worth reading in its own right.
If you are interested in learning about kombucha tea, I'd definitely recommend this book.