The general tone of this movie is quite dark, especially at the beginning: the world is freezing over, a pregnant mother is walking with desperation to the midwife's house on a hill, the baby is born with a frozen heart and is seemingly lifeless while the midwife works on him. When she installs a cuckoo clock for a heart, his re-animation is disjointed and a bit creepy. The birth mother leaves the baby with the midwife and the midwife raises the child.
The midwife makes rules about not falling in love as she says it will destroy his heart and kill him. The rest of the movie is about the boy falling in love. Each time his 'heart' gives him trouble, his actions become stiff, awkward and intermittent in a disturbing way. He is tormented a lot by the school bully. Chased down a train by 'Jack the Ripper' with a knife describing his ill intent in a sinister tone.
A number of characters at a side-show style amusement park are 'interesting': a girl's head is separate from her body and attached like a balloon, one character has two heads, another is a face with a bunch of legs sticking out like a sun, another lives in a coffin, chain-smokes and is mean and creepy.
A number of 'dream sequences' show fanciful imagery and adventures of the characters which could be hard to follow by small children.