I just finished this (after buying it yesterday). It was really intriguing, and like you said Cat, so different to the things I normally read. At first I though the idea of unseeing and unsensing things was a little too strange and unbelievable, and that it was just going to have to be one of those things for which you have to suspend disbelief in order for the story to work. As I got further in though, I thought maybe it's not so weird after all. We often see what we're expecting to see or what we want to see, regardless from reality, so if you're bought up in a place where unseeing things with certain characteristics is the norm, why not?
From about page 80, I was convinved that Orciny and Breach were the same thing/place, and I was really pleased when it turned out I was wrong. It makes reading more exciting when the author gets the better of me :P I think I followed the story pretty well for the majority, but towards the end, things got a little hectic. So maybe I'll reread it one day (in a few years, because I generally find it hard to reread thrillers).