I'm always reading something, usually multiple books at a time.
I have gone straight from listening to this one to its sequel, Where She Went. I'm so glad that I had them both loaded on my mp3 player, because HOLY CLIFFHANGER. I can't help but think of these books as a unit and will hold off on reviewing until I am through the entire series (don't know if this is just a duo or if a third book is forthcoming).
Update: It's a duo. I read the second book and reviewed it here. The review contains spoilers for the first book but not the second. Do read these books, but make sure you have them both so that you can jump right into the second the moment you finish the first.