I liked the dystopian setting, the world recovering from such a huge disaster and the fact that it was not full of new techs and sci-fi wonders. I likedloved Sin (eventually) and look forward to learn more of his past. I liked the missions and the interest they added to the whole story. I liked the chemistry between Boyd and Sin and how their attraction developed gradually instead of in-the-blink-of-an-eye.
I didn't much like Boyd after a point; he's whinny, self-centered, stupid most of the times and too pathetic to be considered a successful agent IMO. I didn't like the number of holes in the plot, the dragging in parts, the pointlessness in some of the missions. There were also quite a few typos & mistakes, conflicts in the story itself and in short it needs some heavy editing to show its real worth (which editing I'm hearing the authors are doing right now).
Despite its faults and its length, it was easy to read and hard to put down. I don't feel compelled to go on with the next book right now, but I don't think it's a series I'll leave unfinished interminently.