As art it was terrible but the pre-teens loved it: Teenage Mutant Ninja Turtles, reviewed  

Teenage Mutant Ninja Turtles (TMNT) began as a joke in 1984, a parody of the superhero culture of the time. It was originally a comic book but the stories have since expanded into toys, TV series and films, both animations and acted. The films have grossed more than a billion dollars and are likely to go on grossing down the generations of pre- and early teens. I am telling you all this because I have only just found out and I have never before seen any other TMNT products.

The latest – Mutant Mayhem – is an animated film. It is drawn in a style that suggests the animators were angry as they worked, perhaps because it is set, like all the stories, in an extremely dangerous New York City.

The turtles – Leonardo, Michelangelo, Donatello and Raphael – mutated into garrulous and ultra-violent teenagers after contact with something slimy in the city’s sewers.