This was incredible. I really love Klara (and Rick, although most of the other humans in the story are rather awful). The world building is great and Klara's view of the world is quite something. The voice of the narrator is easy to listen to. 
I felt happy and excited at the beginning of the book, and while my enjoyment didn't change, I definitely noticed the happiness of the story deflating gradually through the entire book. It's a little slow moving in some parts but in a thoughtful way, not boring.
The ending was extremely sad. 

I wish I could know what happened to Rosa in order to properly mourn.