If you’re looking for a comprehensive but readable survey of the beliefs of Ancient Egyptians over time, this should definitely do the trick. It’s an overview, not an in-depth dive into all the ins and outs, so if this is actually your area of study, you’ll obviously be wanting to go somewhere else — but I wouldn’t say this is really aimed at the casual reader, either. You need to have an interest in the topic, at the very least, or the level of detail would be too much.
I wouldn’t say the book is brilliant, and its style is definitely not “unputdownable”, but the topic was interesting enough to carry it for me. And I enjoyed David’s approach, which took things in chronological order and looked at the way religion changed with politics (and/or the way politics changed with religion).