Demon's Souls is what gaming used to be. Challenge. Simplicity. Satisfaction.
If you miss out on Dark Souls, you're turning your back on your childhood days of grinding away at challenging games like MegaMan.
EDIT:
Things I wonder about Dark Souls:
Will there be an equivalent of a Nexus and separate worlds or will everything be part of one open world? I think I'd like an open world where you go out on quests.
Will there be any "towns" in the world?
New moves!?
http://www.youtube.com/watch?v=w6sPHs2EQfc&list=PL7C0363B28999DF20
"I would have told you but I wanted to see you die"
This must be the design motto.