That's what you really need to know about this one. It's a thriller. Seemingly like many people I got tricked by the rather arty Penguin covers into thinking this was a "modern classic" exploring themes of evil and human nature. It's not. Arguably, it tries to turn conventional morality on its head by persuading us that we can all sympathise and empathise with murderers, but it doesn't achieve this - the plot is too far-fetched for any serious literary pretensions. I wasn't persuaded and I didn't see relevance to my own life. If you want to call it a "classic" in the conventional sense (i.e. something that goes on shelves near Austen, Dostoevsky, Tolstoy and Dickens) you must be pretty cynical about the state of modern literature. There are much better candidates out there.
That aside, it's a good thriller. If, like me, you found the Da Vinci Code unreadable, you'll have a much better time with this. It has suspenseful prose absolutely nailed. As it turns out, the book doesn't really have much action in it, but somehow I thought some dramatic twist was about to happen at the turn of every page. It really is that clever. All the irrelevant little detours seem loaded with tension, as the slowly dawning realisation ("How evil are these guys?") starts to cast a long shadow over the narrative.
In short: Nice thriller, great fun, shame about the false advertising.