I really like all the little secrets and trinkets you scattered across the game. The platformer physics feel very nice to use, however the spike hitbox are very unforgiving. It's not a big deal since there are many checkpoints but It may be better if hitboxes were smaller. Usually in platformers like this one, spike hitboxes are smaller than the visuals.
The speedrun timer is a nice addition. As a speedrunner, I couldn't help trying to set a good time :)
The respawn mechanic is quite exploitable. At the beginning you can skip a part by running into the spikes you can skip some checkpoints before the part where you have to do the level backwards so you don't have to play every room. I got a time of 2:58.