Dr. David Jeremiah says that the angel craze "peaked in the 90s" (p14) so the question of why this book was written is a justified one; there must be a pressing reason to release another book on the subject. What I found was that there really isn't a pressing need other than the author's desire to publish his opinion for a new generation. This is not to say that this is a bad thing. Many times a topic may have been done before, and even better, but a new generation may read this newer version and be introduced for the first time to the topic. Angels is a book like that.
I found the book most helpful when I considered it a resource rather than a standard non-fiction treatise. Chapters like, "Showing Us How to Worship," "The Angels and Us: How Much Alike," and "What Angels Are" are great resources for those with questions or putting together a sermon or study. The chapters are Biblically based with scripture and also references to some of the previous works on the subject.
The book is an easy to read, interesting study of angels for a new generation. I recommend it to those who have an interest in angels either for themselves or for someone that they know that may have unorthodox notions.