This is clearly not a "Huge Flat in City Center". It's a good-sized room with a sleeping alcove and a kitchen alcove. At least there is a door on the bathroom. Furnishings are at a bare minimum: a bed, a table, a desk and a couch. No comfortable chair, although there is a desk chair and there are two kitchen chairs. It would have been nice if the kitchen included a frying pan.
A severe safety problem, which I have pointed out to Jonas, is the bathtub. The bottom is curved and very slippery, making it too easy to slip and fall. I have suggested to him that he either provide a rubber anti-slip mat or have the tub bottom etched. It would add a safety boost to intall a grab bar. And finally there is need for a second towel rack if he is going to rent to couples.
I realize that the legal requirements for rentals differ and that it is necessary to take that into account, but nonetheless I must point out that in my home city it is mandatory to have grab bars in bathtubs of rental units. I propose that for Air BnB, this should be part of your safety policy.