This is a shallow reference. The book covers pretty much everything but leaves a lot of unknowns. It is very superficial. For example, it doesn't discuss the challenges around the fact that proxy and caches often have a hard time with the difference between no-cache and no-store. Another example is the lack of documentation of some of the headers, where the syntax for multiple values is unclear: for cookies, what is the separator when you add an expiry? Yet, that's exactly the type of information I'd like from a quick ref guide I paid for.
You are better off with the RFC2616, which is more detailed yet better structured and clearer, and less verbose. It just tells you what you need and exactly what you should or shouldn't do. This book does not provide any value over the rfc.