I will have to go with The Lost Prince by Julie Kagawa.
It’s the first book to the sequel series following The Iron Fey. While it wasn’t bad, I was expecting something… more. Instead I found that it was more of a repeat of what happened in the The Iron King, but not. I am interested in the new story line that Kagawa has set up and my hopes are high for The Iron Traitor, releasing in October 2013. However, while I understand the set up, and fear what’s to come now (DARN IRON TRAITOR BE PROPHESYING THE NEXT TWO BOOKS OMG), I was let down by the lack of … anything really in this book.