My rating is really more a 3.5, but that's not a criticism.This is an spy/action/suspenseful thriller with some science (or maybe SF) thrown in. It's not a genre I generally read; not sure it's one I've ever read before, in fact. Don't think it's going to get me to start reading a ton of action thrillers now but I enjoyed this ride.
The story moves along quickly and is an easy read (I took a while to read it because of other pulls on my time, not due to the book). Our hero is a super(b) spy type and very likable. He goes from one tense situation to another, sometimes getting out of a jam on his own, sometimes with help. There are dastardly villain types, and they come from multiple opposing camps, which helps keep the action going and makes for a more complex and interesting storyline. A lot of research went into the development here: there are a technical details included, often helping keep the fantastic story plausible, though I found they made things drag a bit a few times, too.
I did notice a few glitches in the text; seemed like a word was missing a few times and in one spot seemed like a few words might be missing. This could be due to errors in the Nook version (conversion errors?), and it didn't bother me too much. There also seemed a few times when the flow of the writing bogged down, but mostly it just moved along.