Before buying this book, understand that it is primarily a collection of verses which mention angels and demons. There are two sections, Old Testament and New Testament, with seven chapters between them. The chapters are simply collections from each genre or division of the Bible (Pentateuch, History, Poetry, Gospels, etc.) There is also an index of questions, however there are only 10 questions given.
Each chapter contains brief comments, headings, and Bible verses.
Positives: It is a compilation of passages mentioning angels or demons. A variety of versions are used.
Negatives: There are only small comments which can lead a person off track. The index won't help you all that much.
Other options: If you appreciate this style of resources, I have greatly appreciated Dictionary of Bible Themes by Martin Manser.
Read The Screwtape Letters by Lewis for a humorous and sobering fictional account.
Use a good study Bible (like the The ESV Study Bible) and begin your own study.