I was one, I used to love the show, watched it daily, not anymore. Rarely if ever now. Basically, like others here said, he stopped being funny and balanced and started getting *really* partisan. It's annoying.
I guess I was one of the other five. While I always knew that Stewart was in the mainstream of New York Jewish intelligentsia, and therefor very liberal, he was also the funniest and smartest guy regularly on TV.
A year ago, he and his writers would to take pains to try to skewer both sides. Unfortunately they have become too aware of the fact that they are the major source of news for a huge voter demographic. That combined with their zealous conviction that Bush is a basically an instrument of evil have moved them away from their core competency of smart-assed slacker comedy.
Their mission now is to proselytize their anti-Bush message in a desperate effort to "save" America. Their fake news show has devolved into a fake comedy show whose real mission is to spew strident propaganda dressed as comedy. About the only thing that makes me laugh now are some of the Back in Black segments.