Great start to a wonderful series. I love the characters, and really was interested in what happened to them. If I had to classify this set of novels, I would say it is primarily mystery, although action and fantasy also play a role.
The actions flow logically, given the knowledge of the characters at the time, and the mystery really keeps you guessing until the end of the story. The one caution I would make is that you definitely should read the books in order.
(reviewed 31 days after purchase)