A simple story, beautifully told. The first 2/3 has kind of a mythical tone to it; she brings to ground gracefully, and the last act follows through nicely.
I am baffled by the people criticizing it as something only adults can enjoy. It came to me by recommendations from my son and daughter. It's intriguing enough to keep an adult engaged, certainly, but neither of my kids had any problem engaging with it themselves. I highly recommend reading this with, or alongside, your kids.