This is the all around best book on the topic of Pinhole Photography that I have seen. It's long on explanations and samples of artwork; although, it's a bit weak on practical examples and experiments.
If you only buy one book on pinhole photography, this is the one to get. It provides the background, the basics of how to do it, and plenty of examples of the diversity and richness of expression within this area of photography.
I'm starting out in Pinhole photography and looked around for something that would give me a good grounding. To be honest, I haven't even got to the section that deals with actually making your own camera (I'm only half way through)... the first half all looks at the history of pinholes and how they have been, and still are, used. This is well researched, full of illustrations, and gives a kind of how-to grounding that many how-to manuals don't ever achieve. I'd recommend this to anyone with an interest in capturing light!