Jar Jar, to me, had a decent character development in Attack of the Clones as Padme's Advisor and Representative of Naboo.
Are you kidding me? Jar Jar was a sell-out by Lucas in order to target younger audiences. He was the add-on comedian even though we already had the Laurel & Hardy duo in C3PO and R2D2. If we had to suffer his inclusion in the Phantom Menace, then OK, I can deal with that.
*prepares for major explosion*
But to make him a flipping representative in the Galactic Senate!? For him to be the reason that Palpatine receives the emergency powers that lead to him being made Emperor!? *throws desk in the air*
AOTC inclusion of Jar Jar was a blatant effort by Lucas to justify his inclusion of binks into the series to begin with. It would have been much more cool and dramatic to use someone like Captain Panaka from TPM be still close to Padme as a secondary representative; then have Palpatine manipulate Panaka's militant and strong ideas about protecting what seems to be right into standing up and giving up the emergency powers. But Jar Jar? Frakking hate him.
That, plus the killing off of Darth Maul way before he should have been. I think the fact that they show him walking around in the Clone Wars tv show is because Lucas regrets cutting off such an interesting character too soon.