I think the key thing to remember with HD broadcasts is that a lot of the PQ is dependant on the source material and the transfer methods (if any). As stated by many, . . . some shows/movies are fantastic while others are IMHO, not much better than the DVD.
Any show shot with native HD video is just outstanding. These will tend to be the sports events, award shows and other live broadcasts. Some of the sporting events are just amazing!!! After those come some of the TV shows. For these it comes down to how the show was originally captured and then made available for HD broadcast. Some shows still capture with film and go through a conversion, others are starting to capture with digital equipment. As stated, the CSI shows are just stunning, . . . makes you squirm a bit during the autopsies. Most movies also go through a conversion, so again it comes down to how it was captured and the conversion process. Star Wars Ep II (captured digitally) was breathtaking in HD (much better than the DVD IMHO, and the DVD was outstanding as well), while others are not much better. One final note, having DD 5.1 tied in with some of the broadcasts completes the picture. It really is amazing to me how much of a show or movie is not visual at all, but is simply sound. Recent example, . . . the US Open tennis, . . . I really felt like I was sitting in the stands!
Bottom line, all the HD equipment is getting better, . . . . all the way from the source to the viewer. Like all technology in its early life, there is a long way it will go, . . . and of course we will benefit.