As a beginner, I wanted a book to help me get up and running with water colour painting. I purchase this book after flicking through a selection in a shop.
I chose this book as the examples were from a variety of artists and unlike a lot of the other books, all appealed to me.
The book is well laid out and each point is explained very concisely.
It's not a book to spend days reading, I spent about an hour reading the first few chapters, fully and skim reading the rest to make myself aware of the various effects available, I then immediately started painting putting into practice some of what I had learned. I imagine I will re-visit various bits of the book as I need to apply some of the other techniques.
btw. If you haven't yet purchased your paints and brushes, it may be worthwhile holding back till you have bought the book, as advice is given.