They're badly drawn, they don't tell you nothing about the character personalities. The colors are awful, with a complete disregard for the basics of design. The art-style is pretty unremarkable.
Decently drawn. Follow some basic schemes of design but are ultimately forgettable and lacking in personality.
Full of personality, with some nice quirks, work excellently in animation, the way in which they fit the characters is impressive. They're endearing.
Iconic, brilliant. Simply the work of a god.