I really didn't like this book. It may have a couple of useful tips. On the whole, though, I don't think it is very good.
First, I just don't think it has many good pictures. Flicking through the book, I didn't see pictures and think, I want to know how to take photos like that. In fact, most of the pictures were pretty unflattering.
Flick through this and then flick through On-Camera Flash Techniques for Wedding and Portrait Photography
and see which photographer you would rather emulate. For me at least, I much prefer the latter.
In addition, I found the style of the book very annoying - it is dogmatic. It basically says, you must use your flash in manual mode, if you want to be artistic. I wouldn't mind this dogmatism if the book convinced me that it was right. But there are not many - if any - photos in this book that I would consider artistic. A lot of them are actually horrible. And, in contrast, On-Camera Flash Techniques for Wedding and Portrait Photography
has some really nice photos in it, and almost all of them are taken with the flash in ttl mode (but with the camera in manual mode).
Similarly, in The Hot Shoe Diaries: Big Light from Small Flashes: Creative Applications of Small Flashes (Voices That Matter)
- another book with much better photos than this book - Joe Mcnally writes "if you only use these cameras in manual mode... then you are taking a souped-up Ferrari and driving it like the little old lady going to church on Sunday. Why do that? Use the technology!" And, regarding the ttl flash: "When do I use it? Nearly all the time..."