Primeflats was amazingly well organized. The communication was top and the check-in unproblematic.
The apartment itself was in a special area, however, well connected to the city centre and surrounded by surprisingly good restaurants.
Talking about the apartments equipment one can say that for a short trip everything was fine and sufficient. For a longer trip I would not stay in the apartment since it is in the basement and because of the WIFI problems which occurred (we could not connect).
Having said that I would recommend this apartment to all travellers visiting Berlin only for a few days.