I think the fact that you have to choose between seeing platforms and obstacles makes this a frustrating experience, and because the character jumps at full strength every time, I'd often jump to avoid a projectile only to launch into spikes above me. The art does it's job and the platforming fundamentals are sound, but playing through this felt like I was always struggling against the game's mechanics, rather than working with them.
I think a more interesting approach would have been to always show the platforms and have one mask actually remove the hitbox of the obstacles, as opposed to just not showing them. As a tradeoff, make the timer much more strict, reduce the amount of hitpoints and have it decrease even faster when using the mask. That way, the player has to strategically switch between masks to avoid running out of time and being able to beat the level.