Well, to be fair, Lucas did say at one point that Star Wars was at least partially intended to be a series of kids movies, so Jar Jar was likely included as a character who would appeal to kids. I've never had a problem with Jar Jar, personally. I think he's funny and the Clone Wars cartoon has made him a much more interesting character. Admittedly, I've only seen the first season, but there are a couple of episodes there (Bombad Jedi and The Gungan General) where the writers showed they can make him a competent ally while still being very much in character.