I've really been impressed with Gallery. They have some good shows that go way indepth about famous paintings. So that's great. I can see though in about a month or so I won't have a use for it as I will have watched pretty much everything they have.
Ultra seems to be really a niche area, showing all things fashion, that I don't really care about.
I'm not big into music so Rave is a bit of a waste. Rush can be fun, but gets boring after a bit. Maybe come winter it will change. Same with World Sport, it can be nice during their CFL games, but they repeat the same game ad nauseum.
I don't have much of a need for cartoons so Animania is a waste, but I check it out sometimes for the classic cartoons they have.
HDNews repeats every 12 minutes. So if you catch a bit on there, you're good for the rest of the day. They don't cover all the major stories either, just ones that they can get an HD camera view from.
I haven't watched HGTV HD recently. My mom seemed to like it when she visited a few weeks ago.
ESPN2 HD... if you watch ESPN2 you'll watch this one just as much. So an easy comparison there.
Just my $.02.