There's a long tradition of eccentric nanny stories, starting with Mary Poppins and Nurse Matilda, in children's literature. There's also the animal nanny motif, although it's usually a dog like Barrie's Nana and Alexandra Day's Carl. Then there's Amelia Bedelia's brief stint as nanny, Clarice Bean's Uncle Ted, and so on. There's also the "bad nanny" sub-genre, which are generally kidnapping books.
Nanny Piggins doesn't quite fit into any of these categories. First of all, as she tells the children, she has no experience as a nanny. Her real job is a porcine cannonball in a circus. She doesn't reform the children (who are quite well-behaved already) or take the place of their parents, or fit into the household in any way. In fact, she's a great deal more irresponsible than the children or their father.
Her first adventure is to take the $500 for school supplies and uniforms and take the children to the amusement park, where they spend most of the money. The rest goes for chocolate and a few school supplies. She makes their uniforms with cheap dye and crayons and when they disintegrate at school she blackmails the principal into giving them another $500....which they set off to spend again.
The story is, of course, supposed to be amusing nonsense, outrageous and ridiculous. However, I found it irritating, especially accompanied by the condescending warning notes about not following Nanny Piggins' lifestyle yourself and the screeds on school, uniforms, parents, lawyers, etc.
I was only able to see rough sketches of Dan Santat's illustrations, since this was an ARC, but they are the only really attractive part of this book. I especially enjoyed Nanny Piggins vintage outfits.