I found the first half of the book to be a little slow, but necessary set-up for the second half, which I couldn't put down. I won't go into details because I don't want to spoil anything, but there was a point in the second half when I thought he could have ended it earlier and in a more interesting fashion (there was one too many twists for me). The ending was OK, but it seemed to kind of just peter out. 
 Overall, though, I really enjoyed this book. Before I read it, I really didn't have a mental picture of Afghanistan; I'm glad to have one, even if it does come from a work of fiction.