So, when I first saw the title, I've got to admit that I was thinking of something kind of like this:
Boy was I wrong.
This one was a roller coaster for me. From Marcel the Shell with Shoes on to an awesome kick-ass historical sci-fi apocalypse setting - which I loved to the point that I am currently mulling over exactly how I want to steal it and make it my own - to an ending that really left a bad taste in my mouth. See, I really hate "victory snatched from the jaws of defeat" stories, and that's exactly how the ending sat with me. The People of the Shell are doomed. Whatever these creatures are, their life cycle probably involves eating up all the biomass and then shooting back off into space (*cough* Tyranids *cough*) (which isn't a criticism - see above re: me stealing this entire premise - theft is great).
Eventually, the monsters are going to finish eating everything and then they're going to move on to the next planet, and the People of the Shell are going to die. Despite his scientific unsophistication, Cyrus's idea could actually kind of work: exploit the invaders but keep their numbers low, interrupt their life cycle when there is still
something alive - chances are pretty good that some animals survived somewhere, there
are portions of the ecosystem that aren't entirely dependent upon sunlight, or don't need a lot of sunlight to cling to life, and life survived the
last major extinction event - and then take back the planet. But the ending cuts off that possibility. If the story had just been of a doomed world and its people's last gasp, or even of how the folly of humans prevents the possibility of rebirth, I could have enjoyed it, but add in that tantalizing glimpse of hope... nope. Not my thing. Some people enjoy it, but I find it really frustrating.
In the end, I can only give this one three out of five stars. It was extremely well realized from moment to moment, and I was quickly drawn in to all the characters, but I really don't like bait-and-switch endings like this. They might not be categorically bad - some people are into them - but they're really not for me.