We had a terrible check in experience!
We were told check in was super flexible and our arrival rather late in the evening wasn't an issue. Our flight had some delay so we arrived even later. When we arrived at the keybox at 00.20 the code wasn't working (because apparently you have to get the key before midnight but we weren't told this) we almost had to spend our first night on the street, but were luckily able to find a hostel that still had space (we finally got to bed at 3.30am!). We were at least refunded for the night we couldn't spend at the apartment, but still lost quite a lot of money due to this incident (cost of hostel+uber to get there)
The apartment is clean and the bed is very comfortable.
The apartment is really far out from the center and you will be spending a lot of time in public transport.
Due to my horrible check in experience and the what I felt to be a lack of accountability from the host in our communications I would not recommend this place and would not stay here again when coming to Berlin.