Stephen Colbert, Jon Stewart, and partisan humor

From an interview with the author of Colbert's America: Satire and Democracy:

FOX411: Do both Republicans and Democrats think he’s funny, or is Colbert’s humor partisan?

SM: Colbert appeals to a much broader political spectrum than Stewart…. Colbert’s charisma also helps him. Stewart will annoy people who disagree with him, but Colbert is the kind of person that most people just want to be around.

I watch the Colbert Report most days but the Moment of Zen is about the only part of Stewart's show I find interesting.