It started off as a good children’s story. The little girl is tormented by a troll while living in a magica forest. She decides to set off on her own, and the reader can marvel at her strength and endurance, while also seeing her vulnerable side. The characterizations are excellent.
Then you get to the end, and wow. I won’t spoil the twist, but if you’re like me, you’ll have to reread the book with the twist in mind.
That twist takes it from a good story to the kind you want to recommend to everyone.