My two euro cents on Futurama:
Futurama seemed to suffer some teething problems in that it thought its principal characters were more interesting than they actually are. Fry (the twentieth century pizza delivery boy) and Leela (the one-eyed alien girl) just don't have much going for them as characters, although Bender (the robot) is a pretty solid comic creation.
The Simpsons went through something similar, not really hitting its stride until its writers realised that Homer and not Bart was the show's central comic anchor. Futurama has learned to make up for unengaging central characters through sheer comic brute force, in some ways matching The Simpsons for density of gags. However, it will probably not rival The Simpsons for lasting greatness until it delivers enduring comic creations along the lines of the characters that inhabit Springfield.
See the soon-to-be-created node: Simpsons Characters of Unimaginable Comic Genius.