First, the good stuff: the apartment's location is great; all the monuments are within easy walking distance. The communication with the owner is very good and he answers promptly.
Now to the bad. The flat's cleanliness isn't very good, and it could use a deep clean. But worst of all: there are cockroaches. Massive ones. We slept with the lights on. This problem should be addressed before the flat is rented out again. As it is, it isn't suitable for habitation.
Luckily for us, it was only a short stay.