Lucas conducted exit polls around the release of TPM and he found that Jar-Jar was actually a hit with the target audience (children) and a lot of women loved him as well. He says that most of the complaint came from 30 somethings on the Internet.
He says there is always a group of people who don't like comedic sidekicks. There were some fans who thought the droids were horrible in ANH, some fans who couldn't take Yoda seriously because he was a muppet, some fans who didn't like the ewoks, now there are some fans who couldn't stand Jar-Jar.
But I would say there are far more people who think he's not all that bad, even if they think he could have been better.
I'm 35 and I -love- Jar-Jar.