A solid, well-written mystery with a great protagonist (the extremely analytical Mia). It grabbed me right away. There were a few holes in the plot early on, but those didn't bother or distract me too much. Also, the happiness quotient concept is interesting, but after a while I felt like it was being a bit overexplained. Overall, though, I enjoyed it a lot, and I thought the audiobook narration by Shannon Tyo was very good.