I guess it depends what you're into. So far I've enjoyed loads of stuff on HD and to be honest have become a bit of an Addict!!

Most of the stuff I watch is on BBC HD to be honest but the following have been good/enjoyable on SKY HD
lots of stuff on "Discovery"
lots of stuff on "Nat Geographic"
lots of stuff on "Artsworld"
ocassional stuff on "SKY One" e.g. "The Cable Guy" "Mysterious Island"
I didn't think "The Hades Factor" looked much better than SD to be honest. I find the difference is noticeable on people's faces, e.g. how much you can see their complexion + on very small writing. For example, in "Bleak House" you could see every blemish on the cast's faces and you could read every word in each of the letters (I paused one and read the whole content

) but in the Hades factor, flesh tones were'nt very clear and some of the letters on signs in the movie were difficult to read. For me, this is usually the first sign of upscaled content as if these small details are blurred in the original print, they will stay blurred in the transfer.
Gae