Robert and his wife Nurcan were very friendly, nice and helpful. The flat itself is plain awesome, cozy and classy. The neighborhood basically looks like a small village in the forest, very beautiful and relaxing. Also if you're visiting some event at Olympic Stadium, it's just 10 minutes walking away! The groceries are about 15 minutes walking away, there are cafes and bakeries in the area. Next time in Berlin we're definitely asking Robert for accommodation again :)