A very fun and entertaining book.
Since this book was originally written in the 1930s, it has the distinct style of old children's books. It is very unrealistic and silly, but still a very good read.
I really enjoyed the ridiculous plot and funny situations that the Popper family and the penguins find themselves in.
Many of the things are outdated (Mrs. People's focus on tidiness, animal licence and ethnic treatment, people not knowing what a penguin is), but it is still readable today. I would suggest some adult assistance for very young readers to give some historical context on the pre-internet, pre-computer world.
A very good read. Highly entertaining.