I guess I'm in the minority when I say that the Pentatonix appearance was one of my favorites of his so far. Maybe it's just because I've gotten so use to his Kermit already, but I really just felt like I was watching Kermit and Constantine.
As for the Muppet Thought of the Week? Blegh. They should just scrap the ones they recorded during the first sessions, since he has improved so much since then.