"Challenging" was the first word I heard used to describe this book. I think "surreal" was the next. Following that was "impossible to describe." Even the author herself, when asked to describe the book, talked about the themes and ideas that led to its creation without attempting to describe the plot or characters.
Other descriptions they could have just as accurately used: captivating; insightful; imaginative; perceptive; funny; and enlightening. That this book is unusual isn't the first or most remarkable thing you need to know about it, but that it powerfully and effectively conveys