Pages Unbound when they reviewed it. It sounded so fantastic I decided to hunt down a copy and read it for myself. And, it's truly a really good (although fairly-short) read. After all, I grew up on a diet of Disney movies (why don't they show the classics anymore?) and I thought I knew quite a lot about fairy-tales.
This short book (or if you have another viewpoint, long essay) is 27 pages long, but does a good job of introducing and discussing the genre of fairy tales. First comes the definition, which is really more of a discussion on the nature of this genre. A quick look into the history follows, their target audience (is it really only meant for children?) and other topics.
What I really love about the book is how well-read Tolkien is. I like to think that I read a lot, but clearly, I'm not even a small fraction of how well-read he is. So here's a note of warning, you may not want to be like me and read this book on a train. Instead, you should read it in front of a computer or compilation of fairy-tales because you will want to start searching to find out more about all these wonderful tales Tolkien references (you don't need to if you just want understanding, but it's so much more fun to do so).
Of course, the prose is fantastic. (I don't think Tolkien could write otherwise). At the risk of gushing, I will say that's it's a joy just to read. Even if you don't fully understand (and I had to re-read many sections a few times), it's still wonderful how the words just flow over.
Basically, this is an excellent text. If you have an interest in fairy-tales (or just literature in general) or you just like Tolkien, you should really read this book. The only way I can think of someone to not enjoy this book is if you happen to hate well-written non-fiction on a genre that we're all familiar with by an excellent author.