This is such a beautifully written book. It doesn't get bogged down in excessive and lengthy descriptions and yet is able to capture every moment in perfect clarity. The relationships formed are moving and believable and the sense of the inevitable end from the very beginning of the story really drives the narrative. 
Being narrated from the perspective of a child, it is not particularly convincing that she would think in such a philosophical and clear way, but this didn't really draw away from the novella for me, though I can see why it would annoy some. That is probably my only criticism.
Truly such an incredible use of so few words.