Reading this has been more infuriating rather than educating.
I am in no means trying to say i'm well more educated than the author on the topics, but let's just say i've read a lot of esoterics books focused in angelology. Don't get me wrong, this is probably a great book for a beginner that want to study the topic ( or not, i will elaborate later ). But 75% of the abrahamic angelology ( if that what you're looking for ), is a general knowledge you can find easily on the internet ( even Wikipedia delve deeper into some of the topics here ). I reccomend this book as some short of keyword source, if you see anything that peak your interest, you should do more research on your own. So probably reccomended for introduction, not for further study.
Back to why i called this book infuriating. I thought that this book would focus on abrahamic angelology because the belief itself 'create' the image of your modern world angels. However the author also talk about other beliefs and folk lore connected to angels beside abrahamic's one, which would be insightful if he didn't start mashing up those religions, that clearly have distinct line with each other to fill in the gap and draw his own conclusion. Most of the times, he even insert his own opinion and view without making it clear that it's an OPINION not fact. This remind me of the method some ancient greek philosopher use by inserting their opinion in the middle of a list containing facts and proven truth in order to pass it on as a fact. This could be quite annoying if you're a beginner reader who then take his opinion as fact, not knowing it is not and cause mass-misinformation.
He also skips a lot of topic, beginner readers seems to like to read about like the specific angel order/choir, the seven archangels, etc.