While Kaestner's book, written in 1949 right after World War II, focuses on the political content, the film is most striking for its images: very brightly colored, mostly in agitated movement, spanning vast ranges of styles not to be expected in an animated movie: landscapes in the style of romanticism, traditional silhouette, some iconography bordering surrealism, lots of people and machinery reminiscent of George Grosz, a bit of Pop Art, but, above all, the aesthetics of the Hippie generation: Light, gay, psychedelic colors, flowers and small peaceful birds all over the place. Given that the film was turned in the same year that saw Woodstock, and the fact that the content is a pacifist parable, turning to hippie style is perhaps not to be wondered at. The sheer fireworks of colors makes the movie worth viewing...
Deplorably, though, the film team was so keen on playing with colors and pictures that several other aspects required to make a good movie have been neglected. Even though they had a good basic plot to work on, it is rendered in a rather sketchy way. There are long stretches of cheap slapstick comedy that could have been left out without any loss. The characters remain unconvincing, inexpressive and schematic and do not evolve during the plot - least of all the children, even though it's the children all this is supposedly about. This is particularly surprising and disappointing since the movie is based on a work of Erich Kaestner, a writer most famous for his vivid and affectionate depictions of children's characters.
Young children will, no doubt, enjoy the colors, the pictures, and the slapstick. Still, this is not just a movie for children. Children of about six years or a bit more will miss many of the political sub-tones, and in fact, when i was watching the film, quite a few times children in the auditorium loudly complained to their parents: "What is this, what is happening now?" My impression is that the film-makers rather played on their own imagination, their own tastes, and their own connotations, in the world of grown-ups - up to and including, just to name one example, an allusion to Nikita Khrushchev hammering the U.N. conference table with his shoe, an event that happened ten years earlier and would hardly be known to young children, even near the end of the Sixties.
I don't know whether Kaestner liked the way the film-makers played with his book, obviously rather for their own amusement than for pleasing others, or even pleasing children. But he might have, for he once said: "Only those who grow up but still remain children are human."