This game is brilliant in almost every way. Let me start about with a few criticisms though. There is definitely a drop in performance when you load a save. I don't know if it's unoptimized reading of the file or something; but it's noticeable at best. At least for me, it might vary across devices.
The artwork direction was very good for this demo, I really loved the color pallet and contrasting hues and colors that you used. The main "brick" tile was pretty mundane after a while, I suggest making a cracked variant and spreading it across your rooms.
Overall, very fluid animation. It's definitely your strong suit. The satisfaction of landing a perfect movement combo feels really nice, but I think that the specific rules of movement were introduced a bit too quickly, maybe a bit more demonstration of how to preform an off-the-wall air dash double jump.
Not to say that these skills can't develop, but It would be more fun if these skills were taught earlier on. I haven't played through the entire demo, it's pretty hefty and generous. I will definitely keep an eye out once this game is available. Thanks for giving me and others a great experience, whether or not they liked it.