We (two couples) stayed here for one week. We arrived in Berlin late, but the Andre found the time for us even so in was Sunday. He showed us our place and was very kind and helpful during all our stay.
The place where we lived was very clean. The weather in Berlin was pretty cold and it was very pleasant to come back to very warm apartment.
The apartment itself is located in zone B. The nearest tram station which can lead you practically to Alexanderplatz is right on the way out of the apartment, which is also great.
I would definitely recommend this apartment.