Surprisingly good for something under 200 pages. A good base idea and a likely outcome.
Assumes, like most SF, that humans will get to the point where they'll no longer depend on Nature before they'll harm it so much that it'll destroy them in self defense. I find that laughable, but I guess it's kind of hard to write SF without assuming that.
Besides that part and the ever-present human evilness, saying it again, surprisingly good.