The Daily Show has done a great job carving out its own niche in the comedy landscape. Jon Stewart has a great comedic face, as he goes from deadpan to mugging for the camera and back.
Over the years The Daily Show grown a bit predictable, the biggest sin a comedy show can commit. Because it's so reliably left wing, it has more trouble being funny when mocking the Left. Partly this might be the studio audience which prefers more anti-Republican jokes, partly it's the personalities and political beliefs of the writers showing through.
We'll see what happens going forward, hopefully The Daily Show can show a little backbone and mock everybody in power -- even their fellow left-wingers.