This is a surprisingly deep metroidvania. I got pretty far and then got a little stumped (I unlocked the ability to swim/move in the green goop and then couldn't figure out where to go next), but you fit a lot of content into this!
I really liked the overall design of the level. It felt like every time I unlocked an ability, not only could I proceed through an area that I had previously been blocked, but I also usually found a secret (a health upgrade or slowmo upgrade). Really great work placing secrets throughout the world! You nailed the metroidvania aspect!
Like others have mentioned, the combat felt a little clunky. It usually felt like I couldn't fight enemies without losing at least a little bit of health (since they tend to bump into you pretty easily). I found the wall jumping to be pretty smooth. I think I liked the air dash the most, since it had some nice usages later on in the game (like dodging the room of 4 exploding bats).
Great work!