I would say PQ is very good on most channels, with Discovery HD Theatre being excellent, and the local PBS station being ok, to pretty poor, depending on what is happening at the time. When I was watching, "The War", I saw all kinds of the weird artifacts that only the PBS station has during some scenes, but other times, it looked pretty decent. Their problems seem to consist mostly when there is fast motion on the screen, and I may be nuts, but black objects seem to cause the most problems. No other local or national channel has this same issue.
ESPN 1 & 2 look pretty good, to "fuzzy" depending on what they are showing. I think they say stuff is HD and it's not, it's just stretched and "Shown" over the HD channel. They had something on a couple days ago, and it looked really fuzzy, worse than ESPN 2 SD.