This place is really nice, just between Kreuzberg and Neukölln.
The flat itself is big (definitely great for 4 people) , clean, and has this Berlin touch in the decoration that is super nice.
The bathroom is small, but like everything else, very clean, and the boiler definitely has enough hot water for 4 people (I think it's one of them that heats real time, so you can enjoy nice long hot showers)
The kitchen is furnished, you can even do toasts and there is a small balcony that gives you a nice view on the street.