I just got done playing the full game for a couple hours. I haven't played the demo, but judging from what the article says, I can tell you that here is a lot more to interact with in the full game. It's not really a high key action game, and it's not really a horror game either, but you simply explore and look for things to interact with. Some items can only be used by a different character, so you'll need to come back when you play that character.
It's $10 and I haven't played anything quite like it before. I'm satisfied with my purchase.