Very good apartment for the money. Despite it's located on the far end of the city, it's very easy to reach, with just 1-2 minutes to bus, a few stops to U-Bahn, and another bus to S-Bahn, so you easily reach any location in the city (use the transportation company BVG app, or simply the Google Maps).
Also, the apartment is located just 15 minutes by car from BER airport, very convenient.
Sylvia is responding very fast and she's helpful.
Unfortunately, we didn't meet in person, maybe next time.