3.5-4. I really liked Lady Emma. She had a fun and surprisingly down-to-earth personality that drove Kenny bonkers. Kenny and his lazy approach to everything really didn't sit well with me in the beginning, but he definitely grew on me as a character, especially when I saw how much he wanted Emma.
I really really didn't understand that one thing he did with the spying, though, or why Emma forgave him without much groveling. I liked the story and the characters, though, and the secondary romance was also fun to watch. Light and enjoyable with a bit of a bite - sort of like a lemon meringue.