I hate to admit it, but I was a little disappointed with this book. There are plenty of interesting characters, especially the mysterious and deadly Father Godin, but I think this book was begun without a really strong grasp of how it was going to end.
Essentially, this book takes place in the American Southwest, but Annja winds up traveling all over the world in the quest for her answers. She is attacked in Mexico City, in the Philippines...really everywhere she turns, someone's trying to kill her. While this makes for a lot of cool battle sequences (Annja's body count in this book is insanely high, easily the highest so far), it makes for a very disjointed novel that seems like it is just that - a series of battle sequences.
The overall "monster" of the book is also very weird. A series of black, ominous creatures with red eyes and a strange screaming cry are popping up all over - are they demonic, extra-terrestrial, or what? There is an explanation at the end, but it is something of a non-explanation. I really do think the author wrote himself into a bit of a corner and wasn't sure how to end the book.
As mentioned in the beginning, the saving grace of this novel is Annja's rival / partner in crime, Father Godin. A real Inquisitor for the Vatican, he hunts down all things demonic, evil, or just plain in need of an old fashioned killing. He comes off as one of those older, veteran warriors who are so cool if done right in an action novel, and his interplay with Annja makes for a great story.
In summary, if you want to read this book for the sake of completion, it's not awful, it just isn't as good as the others in the series. If you don't really care about being consistent in which volumes you read, I would skip The Chosen and read the next volume in the series, which I found to be a lot better.