Well, I thought this was a clever fable, and my niece liked the story, too. It does involve the Noah's Ark story, so anyone who is not into Biblically oriented stories may not enjoy this story, but I would not say that there is anything particularly religious about it. It's just that the scene happens to be on Noah's Ark.
At any rate, while my niece and I liked How the Manx Cat Lost Its Tail just fine, my nephew was freaking out. He kept saying that it was too scary, and while I couldn't quite figure this out at the time, in hindsight, I don't think that the story itself is what was bothering him, I think it was the pictures. The pictures are stormy and chaotic, and dark, and several of the animal's faces do register fear and alarm. Lightning is flashing, the wind is raging, waves are crashing, and the sea is churning. My niece and I thought that the story itself was actually kind of funny, but upon looking at the book a second time through my nephew's eyes, I can see that there is a real disconnect between the humor of the words and the intensity of the pictures. I can definitely see how the pictures might be unsettling to a little kid.