Soulless (Parasol Protectorate, #1) - Gail Carriger Well, more 3,5 then 4 really. Light and easy read that got to be a bit silly here and there and the last chapter of tying all ends together was more tedious then anything. It had some amount of steamy scenes that perhaps is the one thing that keeps it from being a YA book (at least for the non-swedish market, I remember reading quite explicit books in my early teens come to think about it)
Both main characters were likable, especially the heroine Alexis.