I played the demo and I think its a very fun game! The graphics are stellar and I love the artstyle. I do have some minor gripes though.
I feel that the depth perception is a little off in some areas (cloud area at the end and the bridge after the jump pad before the cloud area).
This is a personal opinion here, but I think the game may benefit from a few boundaries on some places. In the area where you first meet the mouse, I was having a bit of trouble getting the fruit as I couldn't necessarily see the bridge that lead to it all that well.
In the in-game menu, I think that different directions for some icons would be nice (pressing up to go to settings as its more up than right).
Some of the checkpoints were a little strange, as it seemed I progressed very far in an area (one before clouds), just to fall and get booted to the very beginning. It felt like I was falling a lot, and I think that more generous checkpoints or maybe just being more lenient on being on platforms/bridges would be nice.
Obviously these are all very minor things, and I think the game is really awesome and I am looking forward to more in the future! Thanks for this amazing demo :)!