Nikolai's place is really nice, it's right across the tram line so the transportation is easy. The room is nice and clean, the bed is comfortable, you can use the kitchen and the utensils as you like. He's a pretty easy going host and very nice and friendly. If you're looking for a private room that is clean and affordable in Berlin, I would definitely recommend Nikolai's place. Maybe bring an eye mask though if you like sleeping in and sunlight would bother you, as there are no curtains in the room.