Hmmmmmm, so first of all, the presentation and UI is pretty good.
So at first I wasn't sure what I was doing. As I clicked on things I eventually understood some of the mechanics. I noticed that the monsters were pretty weak, that I could get faith from them, and use that to raise my health, so I did that for a while. Then, I randomly prayed in an altar, summoned the bad guy and beat it.
So the demo for me consisted on learning the game, there was never really any challenge to overcome, I was just trying things and then it was over. So it's a bit hard to give any feedback really.
(BTW, I recorded myself playing it (without talking), so tell me if you want the footage.)