We were 3 friends occupying this room, one coming from London and the other two from Barcelona.
The day before our arrival the flight from Barcelona was cancelled because of a strike by French air traffic controllers and we couldn't go until two days later. The one coming from London couldn't change her plans and had to arrive and leave as expected; the other two we contacted Tino immediately to tell him about the situation and asked him if it was ok to change it -we would check-in two days later and check-out one day later.
He was very understanding and nicely accepted our request.
Two of us couldn't meet Tino personally since he had already left for holidays when we arrived. The one who met him said he was very nice and helpful.
As far as the room is concerned we found it perfect for 2 people but very small for 3. Anyway Oliver -Tino's mate- offered us to occupy another room as it was available, and he did his best to help us whenever we asked him something.
The location of the apartment is great, literally beside Potsdamer Platz and a good walking distance from Brandenburger Tor or the Reichstag Building.