I spent four nights in Leo's apartment with my 12 year old son. The apartment was very good for 2 persons. It was nice and clean, and we were offered to use the, coffee etc.
The apartment is situated in Kreutzberg, which is a very nice area in Berlin. Lots of good cafe's close to, and just 10 minutes walk away, you will find "The Burgermeister", which presents some of the best burgess, Berlin have to offer. Just in front of the apartment, there is a famous marked three days a week.There is a 10 minutes walk to the U-Bahn, which will take you to all the famous spots in the Center in less than 15 minutes. And a taxi home from Brandenburger Tor is less than 15 euros..
I can fully recommend the apartment for couples or - for a parent and a child.
Look forward to come back.