I liked how there was always something happening in this book, but I noticed that sometimes it seemed like there was action for the sake of action, and it didn't necessarily propel the characters toward the end. The character faces many obstacles to reach his goal, and sometimes the action (for me) wasn't explained in a way that made me believe it was necessary. For example, the hotel in Vegas? Well, Riordan doesn't really explain who was behind that obstacle.On the other hand, the fact that there was always something happening helped keep me engaged in the story. I "read" this in the car as a book on CD, so it was nice that there was something to hold my interest. There are still some things that Riordan left open, and I really did enjoy the book, so I'll be picking up the other books in the series.