I haven't read this cover-to-cover because most of its contents were already covered in my propulsion course; however, it has been an infinitely valuable resource for my project. It contains an abundance of real-life data and examples, as well as in-depth explanations of how and why you should consider a variety of phenomena when building a rocket motor, be it a SRM, a LRE or hybrid.
If you're an engineering student who is taking a rocket propulsion course, by all means, you can rely on this book (and maybe the Humble for LREs). It isn't enough for professional work, but it's an excellent learning tool.