He was innovative and funny when he started, but now he just goes through the motions and people laugh and applaud out of habit. It's like the subjects making the king feel good on Game of Thrones. They're either suckups or clueless.
Seth Myers and Jimmy Fallon are the best currently on. I used to like Kimmel back in the Man Show days but he's become too corporate. And I think they put Craig Ferguson on to make Letterman seem funny by comparison.