The writing wasn't great. I think I laughed once, maybe twice, but they weren't big laughs. All the jokes felt easy and obvious, and the characterizations were almost too broad. Making matters worse, I didn't like the animation style at all: poorly sketched cartoons against non-animated photographic backgrounds. It was bad and distracting, two properties you definitely don't want in your animation.
I'm thinking of tuning in next week to see if it gets better, almost entirely because I have faith in the creative team behind it. But if it continues along this same mediocre route, Sit Down, Shut Up will be no better than The Life and Times of Tim on HBO, another example of a poorly animated and unfunny show, and will suffer the same fate. I stopped watching Tim in the middle of the second episode and never went back.
The TV Nerd gives Sit Down, Shut Up one and a half Final Countdowns out of five.