I actually booked the place for my parents who were visiting me in Berlin but after one night they left the place. Mostly because the ad doesn't clearly match the reality or is dubious in some points.
First, the "private" bathroom is outside the room, that means you have to cross a common area. To enter the "private" bathroom you need the same 6number code as for the room, which is everything but practical and if you forget the code you are just left locked outside...
Also, the ad only mentions "no stairs", but the room is actually on the ground floor and has no window, but a door that goes directly to the sidewalk on the street. Even though it is a quiet street for Kreuzberg, it's still Berlin and you can not let fresh air in.
Breakfast is not clearly said to be included, but "breakfast" and the "own bakery" is mentioned on the ad. From what we understood, it's only just a nice bakery on the neighborhood, with no relation with the place, so nothing is included. The way it is described is very dubious.
Smaller details, the water on the shower doesn't drain properly and there's no curtain, so the whole small bathroom gets wet.
I would like to have known all these details before booking.