Nadjas place is very nice; modern, clean and very spacious. It is perfect for families with 2-4 kids. It is nearby the river where it is possible to swim and close to the old city of Köpenig. It has a big kitchen where you can save money by making your own dinner.
My family had a perfect stay and my teenage son was very happy getting his own room with TV:)
P.S.: if you don’t like commuting, this is not for you. You have a 20 min. trainride to Berlin Mitte, but we never found it a problem.