Mom and Dad get a human baby.
It's cute. I like the art style. It's very colorful and crisp. There are a dog and a cat that live in a house with a man and a woman, and then the man and woman bring home a baby. The dog is worried that the baby will want her bones. The dog and the cat get upset when the baby starts crying, but the cat realizes that he can soothe her to sleep. They start spending time with the little baby, singing songs to her, and playing with her. They started out afraid of the baby, worrying that the baby will replace them, but end up seeing how they are all alike and becoming a team. The baby's first words are "woof" and "meow", and then the book ends with all three howling.
It's sweet. It's a recognition of the important role that pets play in people's lives, understanding that just as it's difficult for children to accept new siblings, it's also difficult for the pets to accept it. Clearly the pets are given human characteristics, depicted as thinking in a human manner, so it probably would also be helpful to children getting a younger sibling to understand that babies do get more interesting and become fun to play with once you get past the shock of newness.