Others told you and I'll tell you too, that being able to move the dialogue with space would be a nice QoL. Also having numbers beside the options would let players just press a button to select the response. All this in the service of being able to play the game one-handed. Since this is eaxctly the sort of slow-paced game one would love to play with a cup of tea in hand.
The lack of music and ambient-only sounds helps out a lot. I can focus on thinking instead of being distracted by the soundtrack. It is also nice that David tags along, instead of being stationary, and having to find him when you want to ask something. I've began to appreciate the simple artstyle, because it let me identify clues a lot easier.
I was kinda confused when the demo congratulated me and let me leave through a door, but reading the commends I suppose I am not meant to solve the scene at this point. Good showcase demo though.