We spent 4 days at Alex' apartment. It's very comfortable, near to the metro station and really close to a lot of shops and mall.
Two minutes walking and you find the metro to reach, simply, every place in Berlin. (A good breakfast in a little cafe on the way to the metro station, let us started the day in a great way...strongly recomended. You find old wife and husband serve sweet and salted...spartan but really special).
We found the house clean, and it was very simple to comunicate with Alex. Great check in and great disponibility for the check out.
Remember to carry everything because in the house you find just...the house. Nothing else.
It has been a good experience.