There's nothing quite like watching analog cable, and noticing... MPEG artifacts?! (See, analog is, well, analog, and MPEG is digital, so......)
Actually, there is something worse.
When whatever computer they're using to decode the MPEG stream screws up the stream, cutting out a few seconds of the episode. (Frequently during some important scene...)
But they've actually gone one worse than that. One night - it actually crashed. All channels, frozen.
Yay Comcast. This is definitely worth the money.