After loving the first two books, I could not wait for this. Well let me cut it short and say this final installment is pretty disappointing.
Unlike The Disciple, the research done to further expand on Azazel was done sloppily. Moreover, not only is the ending about as climactic as watching paint dry, but it has so many holes in it that I can't think of anyone of sound mind who will read it and think "Sure, this seems like a cogent and satisfying nullification of a chief Grigori, fallen angel, and to some apocrypha, the corporeal embodiment of all the evil of man."
Don't get me wrong, this is still worth the read, and about 70% of the book is quite good; however, as with many books of this nature, the author decided to forego the actual written history of this entity and instead created a nonsensical finale that just does not work whatsoever.