My friend and I stayed at Christian's place from the 22nd of June until the 27th of June.
The room is perfect for two people. It could be a bit cleaner and tidier, but it's like staying at a friend's place. The place is close to shops, the metro, tramway, the Ostbahnhof, as well as the East Side Gallery and music halls.
Christian was attentive and left us some tee, oat milk, orange juice and sweets.
At one point my friend needed to sew her shirt and I asked Christian if he had needle and thread in his home. In less than two minutes the neighbour came at the door with needle and thread for my friend.
I would recommend this place for two people visiting Berlin.