As someone with Security + and CISSP, I find this book to be extremely helpful. I would focus on the title of the book where is says, "Beyond."
The book is not attempting to give you what you need to pass the test; its attempts are to have you understand the why's. This approach leads to understanding and remembering concepts that you won't get with "test passer" books.
Overall, great book, looking forward to reading every page to cement important concepts and to research others.