The artstyle was perfectly fine, and the music was pretty good, but I felt the gameplay was pretty deeply flawed.
The biggest thing I'd recommend is to avoid jerking the camera upwards during jumps - it feels disorienting and makes precision platforming a lot harder than it needs to be.
I did also notice a pretty major delay between jumping/running into spikes and the relevant sound effect playing. I didn't quite notice it at first, but when I did, it became pretty grating.
Still, you've clearly got potential. Keep at it. (Happy Pixel Day as well, BTW.)