It was amazingly atmospheric, it really feels like there's darkness hanging in the air. Quite terrifying, still can't say much about that since I haven't finished the demo, but as I said it's amazingly atmospheric.
The problem would be in the creature which stuck on the top room and the tedious task you've to do when you die. Also, is there any safe button? Because it's quite hard for people that doesn't have much spare time to complete this demo in one go.
Edit: It seems I was really close to completing the demo. After crossing the fire the demo ends, which mean I didn't lose too much of a thing. Okay then, very cool