The apartment is located in a good area of Berlin, less than 5 minutes away from an entrance to the subway and, if you like walking, it is 30 minutes to a good part of the tourist attractions.
The elevator was not working during our stay (although it was only a problem getting our suitcases up) and we had to figure out on our own where the stairs were located.
The self-check-in/out with code is very convenient, although there is no flexibility in arrival and departure times (even though we asked for it) we were given information on where we could leave our luggage at a train station since our flight was leaving at night.
On the other hand, the room is similar to a fully equipped hotel room. Despite being 3 people, they adapted a comfortable single sofa bed with sheets.