I have to say I am pleasantly surprised at the quality of those pictures even at ISO 800. Though I would have to see them in full size to be really impressed. I have a Canon A80 now and even at ISO 100 I get more noise than I'm comfortable with. I like to do night time shooting, long exposures, and sometimes I just can't do it at ISO 50 with this camera.
I work in an all-digital camera store, but it's very part time and I don't have the money to upgrade to something better, though when I can I'll probably go with a Rebel XT or whatever is the best in that range at the time.
We only got the F10 and the Z1 in stock a early last week when I was working and I was very impressed with the LCD size and speed, but the lack of an optical viewfinder and the loose battery with no latch to keep it from falling out when the door is open made me kind of iffy about the F10. Otherwise it looks like a great camera, though I'd need some more manual control personally.