Birgit and her family are very kind and helpful. They live in a flat in Kreuzberg, perfect location in Berlin. As many flats in kreuzberg, there isn't a lift in the building but that wasn't any problem for us.
We shared the bathroom with them, it was very clean and we never had to wait.
The room is big and bright and the bed is queen size. The only issue we found with the room is that there are not blinds in the roof windows and we were woken up by the sunlight in the morning. After the first night we used masks to sleep and everything was fine.