-The Flat was a bit darker than what we could have expected from the photos.
-There was an unpleasant smell present in the bathroom. The shower, toilet etc. were actually clean, so maybe the smell was coming from the pipes or the air ducts - it was a little disturbing nonetheless.
-The intercom was not functioning properly and upon reporting this to the hosts we heard back that it will be taken up with the building supervisor - but it wasn't eventually solved during our stay. We had to go down the 3 floors down to the street to let each other in because we only had a single set of keys.
-The walls of the apartment were quite thin, so we heard each noise that the neighbors were making.
In the end, the great location of the apartment has mostly made up for those inconveniences.