I have found this book very informative, and I’d call it a must read for any security professional working in the cloud. In some places, it’s lacking a bit of in depth content, but references to additional material make up for it.
As a study guide for the CCSP, it’s a no brainier that you have to read this to prepare.
If you have done the CISSP, a lot of the content is double - which is rather obvious, since some of the domains are covered in both certifications. Nonetheless, I read it cover to cover, revisiting the material, and found it useful.