I highly recommend it. It's part of the Witches series of Discworld books. I'm hard pressed to find one I don't like, but that is certainly one of my favourites. Although it's full of a lot more humour and wit than I make it seem, it's also not without it's more serious moments. To quote a full description of Elves:

Elves are wonderful. They provoke wonder. Elves are marvellous. They cause marvels. Elves are fantastic. They create fantasies. Elves are glamorous. They project glamour. Elves are enchanting. They weave enchantment. Elves are terrific. They beget terror. The thing about words is that meanings can twist just like a snake, and if you want to find snakes look for them behind words that have changed their meaning. No one ever said elves are nice. Elves are bad.