I really enjoyed this story. As a youngish science fiction reader, I haven't read as many of the classic authors that I should, and it's fun to read the stories that established many of the themes that are common in fiction now. I thought it was great timing that this story was featured around the same time that Ender's Game and Catching Fire are playing in the theaters, since it feels almost like a stripped-down, simplified version of the combination of the two. There's something in the raw immediacy and simplicity of the story that makes it feel almost cutting edge, even though I know that there are "dated" elements. I was actually happy that there was no empathy for the other race, and no sense that violence wasn't inevitable. It feels refreshing in the current context where the "other" is often painted with empathy even as the main character kills them.
On the more technical side, I thought Brown's pacing was excellent. He pulled off the use of the main character's falling in and out of consciousness as a way of marking the passage of time, without sounding corny or forced. Usually, when I read stories of characters going in and out of consciousness, it feels like a cop out, especially when they bounce back right as rain afterwards. Here, the loss of consciousness becomes a pivotal device in the story.
I was unhappy when the roller tortured the lizard creature because it seemed like a lazy way to emphasize the rollers monstrosity. However, I can partially forgive him because the tortured lizard also becomes an integrated part of the story, and the other lizard doesn't magically fix everything for the human because he acted mercifully. I wonder if we're meant to think the lizards were controlled by the mysterious entity?