I watch Robot Chicken but it never struck me as brilliant. I personally find that it feels amateurish when compared to other shows of its type. But I'd be lying if I said I didn't laugh really hard at some of its skits.
The Transformers spots are stand-outs for me. ("Megatron, requesting permission to buy it now!"
) And it's great when they manage to get many of the original voice actors from the shows they're spoofing to reprise their roles. Frank Welker in particular.