The King of Elfland's Daughter is a classic fantasy book. It's without a doubt one of the best known fantasy classics. It's an old book, but it's quite good.
The best thing about this book is the prose. The prose is beautiful and that's the main reason why I like this book so much.
The story is interesting, but I must admit that it's a bit simple. That's why the story can't be compared to modern masterpieces. There are probably many readers, who won't like this book because of the simple story.
If you've never read this book, you should consider reading it. I'm sure that you'll like it - especially if you appreciate beautifully written prose.