When I read a detective novel, it's more than just dessert reading. I try to use it as a brain puzzle. The process is pretty straightforward. A good detective novel will give you (the reader) everything you need to solve the mystery as soon or sooner than the detective in the novel. I simply take in the information and form a theory. That theory evolves over the course of the book as I gather more information and rule out possibilities. The rule of thumb is that if I reach the reveal before I have cracked it, then I lose.
My issue with this one is that it was fairly obvious what happened from about 30 pages in. I don't believe this is due to any special talent of mine but rather just the obviousness in this particular story. I enjoyed it, but some of the fun was sucked out by removing the brain puzzle altogether.