It's a very heavy book. The characters are complex and all get humanized.

Even as the war breaks out in Silo 18, you can understand the motivations on both sides.

The setting was interesting, though a lot was said about Silo 40 and I was disappointed we didn't get to see it.

 It's also very hopeful despite the things that happen. There were moments that were tense and that left me horrified. I thought I was going to be sick during the Elise chapters.