Oh man. Controls are one of those things that really click with some people and not with others. The jump mechanic in Jusant was the most frustrating thing about it for me; I couldn't figure out which way you're actually supposed to move the stick - towards where you need to jump? away from it? and judging the timing on double-jumping was impossible for me. there's a spot in the demo that forces you to double-jump to continue and I was stuck attempting that jump 3 or 4 times.
otherwise, I thought it was a neat demo and the pure climbing bits were really nice (I wish they'd been longer, really). the writing was a bit confusing to start, but if it continues following one "narrator" then I can see it developing into an interesting story. I expect I'll play through the whole thing once it's out!