If possible, I will express my impressions.
The overall visual design is not bad.
There is not enough "grid" on the objects themselves. It is needed in the construction for the exact location of objects.
For example, for placement at the same distance entrance and exit to the building of the trimming.
It should be possible to change the color (coating) service road. Now it does not fit into the general view.
Add abrasions on the markup. So it does not look like new

Marking aircraft parking I did not like. Not very similar to the real one.
The aircraft parking number is very large.
It is necessary to reduce approximately 2 times and duplicate before parking.
Concrete, asphalt and other textures do not look quite realistic. There are not enough details (shadows, scrapes, etc.)
Great wish.
Make the passengers and staff move a little chaotically. And you need to add shadows to people, internal structures (registration stands, luggage tapes, shops, etc.).
Service technicians abruptly move (turn).
I would like it to be more smoothly.
I did not see the runway markings.
I really hope that her type can be chosen.
Because it has different options.
Depends on the type of coverage, the length of the runway, as well as the country.
For example, on light concrete it often looks like this:
White markings with black edging.
https://i.imgur.com/7LkOqNR.jpg
I also hope that you will make such details as:
https://i.imgur.com/6dqkuQS.jpg
https://i.imgur.com/fb0T5V8.gif
And do not forget about marking L, R and C in the runway numbers.
Good luck in further development.

I'm waiting for the game.
And I really hope that there will be an opportunity to build
cargo airport.
For some reason this point in other games not honored.
P.S.
"Of course there is a lot to be polished here. Sometimes we find strange features or possible bugs. E.g. a passenger who can’t find the exit stays in the airport and live there forever like in the movie “Terminal”."
And what, something like that could be realized

For example - passengers were late.
Or just people strolling through the terminal(random event) and photographing planes (planespotter)
