Many people who wrote reviews must not understand that Judith Kerr grew up in nazi Germany. If anything more than a silly kids book lacking all but the absurd, it is a recounting of her experience of nazi Germany and how everything from her family was taken in that experience.
People who wrote that it is about creepy men or hating immigrants just has that lens on when they look at the world in general, regardless of the book.
Timeless classic to those who love silly stories.