The book is written by Anthony deStefano who is the best-selling author of A Travel Guide to Heaven and Ten Prayers God Aways Says Yes To. In addition to being a member of the Knights of Malta (a Catholic military order that was originally formed to protect the Holy Land) and frequently works with Father Frank Pavone and the Priests for Life on pro-life issues.
His treatment of angels in this book is based on Revelation - not information gleaned from psychics and mediums. In this recent interview he says the reason he wrote the book is to make theological teaching on angels more accessible to the non-theologian.
"My hope is that, by doing this, these invisible realities won’t seem so unfamiliar in the future. And the more familiar they are, the easier it will be to understand them and to have absolute faith in their existence," de Stefano said.
In addition to presenting theologically sound teaching about angels, he also does what New Age books on angels never include - a thorough treatment of the devil. " . . . (T)he devil really exists. He is spoken about many times in Scripture. He’s not a 'theological construct,' as some academics have theorized. He’s a real being."
I highly recommend this book and do so with no reservations.