I was pretty impressed by the demo, largely because I was disappointed when I saw that there was combat vs human enemies. I still don't think Dead Space needs that, but what I played in the demo was fine. The chaos that ensued when Necromorphs came into the firefight and starting attacking both sides was a pretty cool moment that we haven't seen in a Dead Space game before. I didn't find the open environments to be as scary as the interiors of the first two games, though they looked gorgeous (and the game still ran at 60 FPS on consoles, which is great). Assassin's Creed III taught me a lesson when it comes to buying games day 1 (which is to not do it in most cases). This won't be a day 1 purchase for me, but I'm still eager to play through it. Hopefully the game is still focused on encounters with Necromorphs and finds new ways to surprise the player, because I've gotten real good at identifying Dead Space monster closets in the other two games.
I assume you're talking about quality standards? EA's and especially Visceral are much higher than Ubisoft. You shouldn't fear.