Played the demo and here are some thoughts:
-It controls fine, no major complaints there. I thought the wall jumping was a little iffy at first but I got used to it fast and then I was zipping along fine. Because I can't(or won't) read it also took me a while to figure out why I couldn't wall jump on every wall (only light side).
-I like the speed and the platforming is FUN. I personally never got frustrated with the platforming challenges but I can see people without as much platforming experience having trouble with some parts. The checkpoints are fair though so you don't get sent back a lot even if you die.
-The only time I got a bit frustrated was when I had to backtrack to kill an enemy I missed and it sent me back to my last checkpoint if I happened to die on my search. Maybe letting you activate which checkpoint torch to use might help? I dunno. It wasn't that big a deal anyway.
-It can be hard to see what's below sometimes especially when you have to move down. This is always an issue when you have delayed camera movement. It's a stylistic/aesthetic choice but sometimes the camera just doesn't keep up enough and it gives you no time to react.
-Weakest part for me was really the combat. I dunno, it's lacking..something. Maybe it's the lack of knockback? I know there is some knockback on the cannibal guy which is better than nothing. There might be design reasons for not having enemies flying all over the place when you hit them but it needs something to feel more satisfying I think. Right now though, the game seems to be more about platforming and less about combat which is fine and it's all about where you want to put focus. Again, the platforming is really fun!
-First time I played, I picked air magic but I pretty much forgot about magic for the most part
. It wasn't until later I found out it gives you another jump (again because I can't read probably). I also didn't visit the blacksmith, I assume you need fire magic to get past the blockade?
-Make the regaining of health and magic by the bouncing tofus instantaneous! (or give me a reason why it shouldn't).
-Are you deactivating the insta-kill crystals out of view? You need to expand the deactivate/reactivate region a bit because now they're "popping" into view on the edge of the screen as you move.