Good choice, nice people on...

Liked: The location of the hotel is superb! It is right next to a subway station, so downtown is 15 minutes away. Also there are shops, restaurants literally on the other side of the street. Uber is also available and rather cheap in Berlin. The hotel itself is not the newest and as a single room they gave me probably the smallest room. However it was looking over an inner garden and was super quiet. The bed was comfortable, bathroom super small, but everything was well operational. The receptionists were exceptionally kind, while the ladies at the breakfast room were a little bit "military style". The breakfast was good, not a super selection, but completely acceptable for a few days stay.
Disliked: There was smell on the corridor, so a balcony door was always open on the corridor, which somehow handled the smell but made it cold too. The wifi was a bit difficult so I rather used my own mobile net. I know it was a busy period for Berlin, but still, price-value ratio could be better.