The single thing that stuck with me about this book after I read it was how incredibly miserable every single person seemed to be. They either came from a horrible childhood (the hero), were just incredibly unhappy with love (the hero's best friend), were mean-spirited, petty and jealous (the heroine, niece), was just plain evil (the hero's father-figure) or had a ginormous martyr complex (the heroine).
A book about a female thief who was stealing from people who promised her money for her pet charity and then reneged and the special spy-type guy who was out to get her, should have been a fun, even sexy romp. This wasn't. Everything was all tortured gazes and suspicious silences and 'woe-is-me' guiltiness.
So why three stars? Well the writing was excellent. Even with the unhappy characters, the book was compulsively readable. The author did a good job of propelling the plot. Yeah, there was a bit of a slow part in the middle where it felt like our super-spy hero was being willfully obtuse about determining the identity of his thief. But the mystery of the stolen letter and the pull between the H/h as well as learning why these people were the way they were managed to draw me in. And she wrote the hero as so enigmatically sexy and interesting that it acted as a bit of a counter-balance.
Also, I find myself interested enough to find other works by this author. At least none of the characters did anything really stupid because that would have been unforgivable.