As with all new software, CouchDb suffers from lack of good documentation. Therefore I was really looking forward to this book. Unfortunately, this book has the same furtive, hasty quality as most online documentation.
The book does an adequate job of explaining some of the design choices in CouchDb that offset it from other database systems. But when it comes to explaining the technical details, it leaves a lot to be desired. Indeed there are a lot of examples, as the promotion blurbs claim. I like the examples that use "curl" to interact with the server, that is a good way to get familiar with the REST interface at a low level. But often important details are skipped and are left as a guessing exercise for the reader. A case in point is the design document in Chapter 5, which is really just incompletely specified pseudo-code.
Technical concepts are not fully explained. For example, MapReduce is mentioned for the first time in chapter 3. But only examples of Map functions are given, there are no examples of any Reduce functions, and no explanation of what they are supposed to do. The book states several times that "MapReduce can be challenging", without really explaining how or why - it leaves the reader wondering what the big deal is. Design documents are equally poorly explained.
Add to that the many spelling and grammar errors, and the whole book leaves the impression as if being written in great haste.