Well, I just finished reading this, and wow, my decision to hold off checking out the prepubs was right! That was one heck of an emotional roller coaster of a story. And the climax of events in chapter 9... Unexpected and yet expected at the same time... As soon as Heartseed showed up, it kind of telegraphed the following events, but that's because of what kind of fellow it is.
I wasn't sure I'd like it, but it was an enjoyable read, but not one of the stories that grabbed me as must buy immediately. That said, I'll be looking into the future books, though it will be a lower priority. For a rating, I'll give it a solid thumb up.