With the huge amount of excellent fiction on similar subjects
available at the moment, there's no way I could possibly recommend
that you spend your money or time on this book. [[Unforgotten by Tohby Riddle]] is better.
Further reading suggestion: For a stunning treatment of angels on a
collision course, I'd highly recommend Lauren Kate's [[Fallen by Lauren Kate|Fallen]]. For a beautifully illustrated novel, [[The Graveyard Book by Neil Gaiman]] is also excellent.