Lots of great children’s books can be read by children and adults alike. This is definitely a must read for adults- the combination of the slightly dubious storyline and simple but brilliant illustrations make for one very funny book. The illustration where the rather peeved big fish who has had his hat stolen narrows his eyes is particularly priceless.
Read it for your own pleasure. Then decide if you want to try it out on your kids. It might not be for all children, but my preschooler was gleefully scandalized.