What a sweet book! I've read a fair amount of 'serious'-themed books this year already, but sometimes, I think I need a little feel-good sci-fi to balance things out. 
 That's not to say that there's not some interesting analysis here RE neurodiversity. Sidra has difficulty integrating with expected human behavior, complete with sensory difficulties and accusations that "of course she can learn to operate like everyone around her, she just needs to try harder!" (to be fair, Pepper's trying to keep her alive, but it's still a lot of ouch in one conversation). I believe that this is intentional, especially when taken in context with Pepper and Blue's backgrounds, and in that sense it seems fairly well done. 
 Pepper's story is equally engaging, and in many ways parallels Sidra's. I'm pleased with the writer's choice to let both plots unfold simultaneously, bring them together to close the loop at the end of the book. 
 The ending is cute, if maybe a bit sappy for my tastes. Does me good to read happy endings, though.