Played through the demo just now.
It definitely did not give me any of the same feelings of isolation and having to survive that Dead Space 1 and 2 did so well. It's just a small portion of it and the level design and atmosphere of the rest of the game could possibly be a lot better, but I doubt it. The Universal Ammo system they added in really does not help matters on that front either and detracts from it quite a bit imo. I also really do not like the fact that they added in enemies with guns.
On the plus side of things: The graphics feel quite a bit better and the weapon upgrade and crafting system is pretty neat.
I'm going to pick it up on release, but I do not have any real excitement for it. It really felt like something was "missing" from the demo. The demo also starts you out with a ton of ammo, med packs, and resources. I think that was a huge mistake to showcase and I hope the full game isn't like that, because it really soured the experience.