I don't do the Twitter, but I've seen him on Chelsea Lately. He's funny. It's weird; I have always been a non-consumer of standup for the most part, but now I watch three of them a day on Chelsea, and I'm starting to know who they all are.
I watched the Jimmy Kimmel show just to see how his standup comedy was (being familiar with his tweets). He wasn't very funny, I felt bad for him. I hope he was just having an off night.