Overall a good read. I was really intrigued by the premise (hired killer decides to bail on a job and protect his target) but felt that it was not done in a plausible way. Also, all the details of the contract killing business and cloak-and-dagger stuff were ridiculously Hollywood. I get that a lot of suspension of disbelief is necessary here but it just felt like too much. But in the end, it doesn't really matter since it's the characters and their interactions that really drive the story. I wasn't entirely convinced by either them; D was fairly complex but Jack's entire identity seemed to revolve around his job and then later, his feelings for D. Still, I felt emotionally involved in the book and was really rooting for the characters.
In some ways, I feel like the ending kind of ruined the book. I'm glad things worked out for Jack and D but overall, it was far too idealistic. I had a hard time believing that a happy end is possible given the plot/situation in the book, and the way that things were resolved seemed really far-fetched. It was like the author just wanted to give her characters an ideal ending rather than do what's best/what makes sense for the story.
Lastly, there were little minor errors in the text that can be caught by more thorough editing, things like a line of dialogue in one chapter "I'll find you" turns into "I will find you" in the next chapter, or a character's name "Josey" becomes "Josie" later on. Rather sloppy and it doesn't even have the excuse of being an ebook because I read a paperback copy borrowed from the library! (Also, I don't think ebooks really have an excuse anyway-- if you're selling it as a professional product, shouldn't it be of a decent quality?) D's accent was also distracting but that's just a stylistic preference.