PLOT: An Irken alien sets off to destroy Earth, using his clever disguise as a human boy for himself and a dog for his robot henchman, GIR. Dib, a paranormal nut-job, sees through his disguise and believes that it's up to him to prevent ZIM from taking over the world.
CHARACTERS: I love all of them! I think that Richard for Zim was a brilliant casting decision.
ANIMATION: unique for a Nick show.
I have to mention that for a TV-Y7 cartoon, it got away with a lot of horrific things. The first episode that comes to mind is "Dark Harvest", when Zim steals the organs of kids and teachers at school and replaces them with household objects.
Which, in fact, is awesome.