I downloaded the playground. Tried pressing C on my keyboard but it wouldn't work so i had to use a gamepad to test it. I love that the grapple feels kind of elastic/bouncy, the aiming was a bit weird cuz sometimes it locked on to walls i didn't want to.
Now keep in mind that what i am gonna say next is based on my personal taste with 2D platformers so someone else might disagree. And now that i mention it, i realized your game controls would make more sense to me in a 3D platformer.
First the speed upgrade i think wasn't necessary, but the base acceleration from 0 to top-speed should be a little bit greater. I would have liked the minimum jump height to be lower, cuz initially i don't feel much difference between just tapping the jump button and holding it. I don't know what to say about the jump upgrade cuz jumps feel floaty but at the same time feel better than the normal jumps (maybe because there is more difference from tapping/holding the button but i don't know).
The main problem right now is wall jumping, it instantly sticks to walls before i have reached maximum jump height, and instantly starts sliding down, also requires the jump input to be super precise or else it won't jump from some small walls (input buffering could help with that).
Then there were some specific parts were it wasn't clear what was just decoration and what was a platform i could stand or a wall but there weren't many. And lastly coyote time and input buffering, these two are subtle but really necessary. Hope i could help.