OK, where to start?
Well, let's start with Natalia, the host, who couldn't have been more helpful and friendly. Check in was as easy as you could want, and the welcome was very genuine and informative.
Now, the appartment itself. It already looks really great in the photos, and in reality it did not disappoint, and felt much more spacious than expected. The additional balcony was the icing on the cake - even in late September (though we got very lucky with the weather). The bedroom(s) were large, the bathroom modern with a great shower. The kitchen is very well equipped, and again, modern and well functioning. Also, a lovely bright dining area and sofa etc. with TV (Netflix etc.).
The area is also perfect - quiet residential, yet only 5 minutes walk to Bötzowviertel, a really nice "Kietz" in Prenzlauer Berg. The M10 tram stops nearby (for Friedrichshain etc) and the S-Bahn is close too - great for the City and Airport (via Ostkreuz). This part of Berlin has a really nice balance of shops and reastaurants/bars.
All in all, 5 stars are fully deserved, and we will definitely stay here again.
Thank you Natalia, we really enjoyed our stay :o)