This film is most famous for its Ray Harryhausen animation; he was a specialist in stop-action animation, in which small clay figures resembling children’s toys are moved in tiny increments and then photographed, frame by frame, until the animator is satisfied that he has enough animated footage.
Very few films use stop-action animation anymore, with the possible exception of certain Tim Burton films (JAMES AND THE GIANT PEACH, THE NIGHTMARE BEFORE CHRISTMAS), mostly because computerized animation has become the industry standard. This film, about figures from Greek mythology, looks cheesy primarily because the stop-action animation is such an outdated method of animating characters.
Perseus - played by Harry Hamlin - is the son of a mother who was kicked off her island for daring to get pregnant by one of the Greek gods. He eventually ends up someplace else, by some arcane machination or another of the same gods. (Dad being Zeus, and this son being Zeus’ favorite, anything can happen in a movie about these characters.) Perseus ends up falling in love with Andromeda, who is unlucky in love largely because Zeus had some sort of falling-out or other with this girl’s boyfriend or something. They go through various trials and tribulations, defeating the Kraken in the process, and the movie ends with the two of them marrying.
This movie is primarily suitable for children.