It was simply great! Very clean and well organized. Ann is very friendly and helps with everything. They were flexible on our hour of entry and leave (we arrive early in the morning and left late in the afternoon...).
Very nice and quit neighborhood. 50m from a great Greek Restaurant with very friendly staff.
The only weaknesses are (a) is that it is slightly far from the U metro and the S bahn (we are lazy... it is really only 5 m walk...) (b) Beware when parking on the street! Be sure that you are at the right spot. We got a 55 euro fine... and I even don't know exactly why...
To summarize- if coming again to Berlin- Ann and Andy apartment is the best play to stay!