Love the game!
Sprites look pretty good, have a very simplistic look and reminds me of Celeste, but it does annoy me to see a thing or two that are pretty offscale. Level design is just great, and being able to make your own checkpoint is pretty new to me, neat.
Song's alright, I can see it getting repetitive after a while, but is not too intrusive, so it does its job.
I think the one problematic thing is the walljump, I find it weird and hard to pinpoint how it works. Sometimes it spins you around and gives you knockback, sometimes it works indefiinetely, sometimes it works once per wall and sometimes it just doesn't work at all.
So overall excelent game!