This is the kind of book I used to read all the time twenty years ago and now I remember why. Indridason is a master at plot, creating memorable characters, and evoking Iceland during World War II and today. His detective has a compelling personal life, is likeable and gets the job done. Indridason balances POVs masterfully-there's never a moment when you wish the writer would get back to solving the mystery.
I can't think of anything that didn't work in this book and this is from someone with adult onset ADD. I will certainly seek out his first book, Jar City.