I overall did find this book to be helpful. It is definitely worth the read. There is a lot of good info to get you going when it comes to the topic of storage in Hyper-V. That is generally how I review these books is did I learn a lot out of the book, not necessarily if the book was comprehensive. I have a lot of experience with storage and Hyper-V, so it often doesn't occur to me if info is missing or not because I already know the basics.
My only problem is very often the book would go into a point about how to troubleshoot something, or how to configure something, and it would gloss over the parts that would be very difficult. For example, there is a section on how to troubleshoot various administrative tasks with Storage Spaces. Flow charts are provided, but then in every scenario if the first few things didn't resolve the problem, trace logs should be used. Info about how to set that up and how to go through those trace logs at a basic level would be extremely helpful. But that is never provided. Obviously, an entire book could be written about how to do that, but a few sentences to get the reader going could have been included. Another is mentioning storage spaces should be tuned for interleaving and column size, but barely any info is provided on how to tune that. I expected a book like this to provide some of that info instead of just mentioning it.
Still worth the read if you work with Hyper-V, and are looking for more info when it comes to storage.