I don't know why you keep comparing him to other FF Villains. I don't like it when people do that.
Would you rather every FF villain accomplished their goal? Or behaved in exactly the same way as Kefka? I think not. Stop getting annoyed because you think he's 'overrated'. You don't like him much and others do.

Instead of comparing him to everyone, and moaning that he's overrated, why don't you just play the game and have your own opinion on him and the whole game as a seperate entity - since that's what it is.

I personally thought that he was ok, but was overshadowed by the real villain - Shinra.
P.S. Rufus is a badass.