I agree with Pyrians feedback in that how far you can go into the ceiling is hard to judge. I also think the gravity is a bit too steep that it makes it a bit hard to get the right timing on things, you just drop like a brick if you don't flap.
It's clear that this game is designed that you die a lot, so I think the death penalty needs to be reduced. At this point it's a pretty annoying penalty with the long death sequence and the sound starts to get annoying as well after a while.
I'd suggest, allow skipping the death sequence with space, make it a bit shorter in general and don't play that death sound and instead play a more uplifting cuckoo sound when you respawn.