I bought this book as I just bought a car that had a modified Mazda rotary (13B) fitted with a 48 Dell'orto DHLA.
I basically needed to understand the basics of how the carb worked before I could then try and figure how to spend time tuning and diagnosing it. I'm more from a fuel injection/electronic control background so understanding this mechanically complex device needed a bit of research.
This book was a disappointment because it assumes you know how the carbs work. I didn't know and after reading the book, am not that much the wiser.
If you already know how the carbs work, it's probably going to be of use to you, but then you probably don't need a book if you're at that stage in any case!