Just trying to characterize this book gets you into trouble. It looks very much like a book for children - or a cross between a comic book and a typical children's book - but most of it would not make sense to kids. It deals with distinctly adult insecurities and complex relationships. On the other hand, the enjoyment I got from reading the book was distinctly childlike.
The central character (at least in one sense) is Fluffy, a bunny who acts very much like a human four-year old; however, a description of the characters or the plot will not help you appreciate the uniqueness of this book. In fact, the plot is very much secondary to the development Fluffy's "daddy" goes though.
While reading Fluffy I had the very pleasurable experience of finding myself caring deeply for the characters, hoping for a happy end. Maybe I am jaded, but that has not happened in a long time. The storytelling is innovative and effective. The art is simple and lovely. As a whole, this extremely cute book is funny, profound and highly recommended. Fluffy defies categories.