I played for a while, had a blast as a geographer and GIS student. Using Windows 10 on a Lenovo Legion laptop with NVIDIA GeForce GTX 1650 and the only performance complaint I have is that I don't see the stars at night - I only learned about them in the comment section here. But atmosphere at day seems fine, the yellowish tint at the horizon changing into blue.
As to suggestions: It would be nice for the marker of correct location to stay on for a while longer, so that we have time to manouver around and find it.
Maybe it would be also useful to rebind controls: speed up and down to W/S and altitude change to e.g. Z/X. It feels intuitive in the game to press W to speed up for me, more than to change elevation.
I believe the game has huge educational potential, but for that it'd need more labels on the map as we fly. The GUI could have the name of the country we currently fly above displayed either around the goal list or even by the airplane itself. Maybe also a "regional mode", where we choose a limited selection of cities available as goals, would be possible - so we can fly only around a single continent or have only country capitals as targets.
Overall great experience and a fantastic, little, relaxing game I love it.