Lovely apartment with a nice balcony and great view! It has everything you need, including a daily workout on the ten stairs to get there ;). The kitchen, bathroom and livingroom/bedroom are spacious, the second bedroom is small but ok!
I don't have a bath tub at home so I was happy to be able to use one during my stay.
Carsten received us in person when we arrived. He is very friendly and responds quickly to messages.
If you don't mind travelling a bit (mostly half an hour by S- or U-bahn) to the "sightseeing spots" in Berlin, I would recommend staying here. It's a nice and quiet neighbourhood close to shops and walking distance to restaurants and bars.