The Titan's Curse in one sitting and immediately wanted to start The Battle of the Labyrinth.
Percy continues to grow into his half-blood powers and learning how to deal with threats against Camp Half-Blood and Olympus. One reason I think I liked The Titan's Curse was Annabeth was not in it much I get sick of her stuck up attitude and how she thinks she knows everything all the time. However with Annabeth gone Percy just seemed lost and unlike himself in a lot of ways.
I loved the build up to everything and the ending was well done. Once again I had a couple issues with grammar in parts.