I think the most interesting plotline there was the fate of the humans teleported to the other world, and I really think that that thread could have been expanded upon...though perhaps that is my own personal interest speaking and not a literary one. Altogether, I liked it.
Things I didn't like:
- The name of the ship "Mission Highly Improbable". Yes, I know that is a reference, but it still felt really, really cheesy to me. "Mission Impossible" might have been a better and more direct homage.
- The italicized intro. It felt like a cop-out when, at the end of the first chapter, you know that he failed in convincing Sano to spare Earth. For that matter, the fact that Earth had to be "destroyed" in the first place. If all they were going to do was wipe out every living thing on the planet and then terraform the planet to be fairly close to what it started out as, one would think that it would be easier and considerably more humane to simple settle on a planet with the right orbital distance and right amount of landmass but no intelligent life.
Things I did like:
- The rift. The description is vague enough that it could be a number of things; it could be a spherical one, surrounding the Kha'lek homeworld, a spherical one surrounding another planet, star, or point, a barrier that stretches clean across space, or one of countless more possibilities. In any case, it is fascinating.
- The creation of the Spacehawks. You did a great job conveying the emotions an entity, previously confined to an unfulfilling life, experiencing the double joy of self-powered flight and the freedom to travel anywhere it wanted to (again, except for the rift). When I read that section, I really wished that I could fly for a few moments.
Well, that's pretty much the extent of my critique for now. Overall, I like the book so far, and I hope you keep writing it.