At first glance, a bit of a pot-boiler but a thoroughly entertaining and engaging race. But I've thought about it a bit over the course of the morning and perhaps it's a little subtler than that. 
 The protagonist, Cardinal Lomeli, is a sympathetic and heroic creation. I can see an opportunity for Harris to revisit his earlier life in a future book (hint, hint). 
 None of the antagonists is inherently bad or evil but simply misguided. All are well-drawn and believable. 
 The twist? Meh, I saw it coming and, while it's not impossible, it's unlikely in this day and age. No one is that... innocent.