Pretty neat demo, but a little rough on the edges (though of course, being a demo, that is to be expected). I think it definitely has a pretty good core to it for now: speeding around and bouncing off of walls and springs felt great when you get your momentum going. Definitely seems to be going for Sonic-esque gameplay and I'd say it's getting close.
That said, I did feel like the demo was lacking some polish (I know, duh, but still). For one, the game seems to lack any amount of coyote time which made it feel bad whenever I jumped from the edge of a platform and it used my double jump instead of making it count as my first jump. In a similar fashion, walljumping felt very awkward in that if you try to press a direction and jump instead of just jumping (which is very typical), unless you do it perfectly in sync you'll usually just fall off the wall and double-jump instead of actually walljumping: I think there should be a bit more stickiness to walljumping, a bit of a half-second buffer where you can hit a direction without immediately becoming unstuck from the wall. Moving beyond controls, with the power-ups and springboards and such having no sound-effects or sparkles or what-have-you and instead just disappearing instantly made the worlds feel very hollow and unexciting, which also combined with a general lack of direction in terms of their being too many routes and no story to work off of. Finally, and this is just my opinion, but the climbing ability felt a little weird and misplaced with the way it kills your momentum and allows you to go up anywhere: almost felt like cheating when I remembered to use it. Again, it might be that I'm being silly in pointing those things out because they are obvious and going to be addressed in the actual release, but I want to play it safe.
Also, I tried to play this game with a playstation controller and it didn't work unfortunately: just something to note for you to look into if you can!