The holographic effect on the tutorial text boxes makes the text hard to read.
Having the tutorial box that teaches you how to jump AFTER a ledge that you can only overcome by jumping is, uh, yeah... kinda silly. XD
This game would really, really, REALLY benefit from "coyote time."
I wish respawning after death was faster.
Sometimes I jump onto a ghost platform thinking it's activated when it's not. I wish the activated and deactivated states were more different, easier to tell apart. It's weird that the activated state is bright blue while the deactivated state is gray, i think that's what's throwing me off...
Needing to go get keys and then re-do the same part of the level just in the other direction is boring, I would get rid of the keys and just make the levels a linear string of challenges.
The movement is sluggish and unresponsive, there are games that can benefit from that but this doesn't look like it's trying to be one of them, I'd try making it more responsive. Less slippery.
Stopped playing a bit after the red dog enemies appear, just kinda got tired. ~
I hope this feedback helps! ^0^