Just finished. Pretty solid. I like these little episode-like eBooks, I wish we had more of them!
The last scene was really what this ebook was written to get to, I think, and so in the end it's justified, though a lot of stuff along the way just ends up being the necessary bits of plot movement to get there. Nothing new is given to us about the nexus, and the motivations for the other characters are too similar to Generations to really be unique.
The first half was good fun getting there, though - I love any chance to watch the Ent-E crew be awesome