Yay, played through the whole thing! It actually feels rather polished, from the graphics to the gameplay.
I did find myself abusing the enemies by getting hurt so that I fly further and essentially avoid the enemy. Since health seems to regenerate, it didn't seem like a big problem to do that.
The flies never really got me, so maybe they need better placement in the levels. For example, they could be planted inbetween crocodiles so you gotta hop over them but avoid the fly, something like that. Or increase their speed, quantity or range.. I'm not sure. I just didn't feel like the fly enemies posed any real threat. Maybe the same can be said for the shooting blobs.
There's not really anything that feels unfinished though. It's just a good little game.