The flat has everything as advertised. Not too fancy, but all I needed for a comfortable month stay.
Before arriving I was slightly unsure about the location, but it is practically on top of the u-bahn that took me directly where I needed to go in 10 minutes, and just a few steps to shopping and a few more steps to go out in Schoenberg.
There was a slight hiccup at check-in, but only because my flight’s arrival was at an early hour, and the usual assistant with keys would be unable to meet me, so a neighbor had been asked to fill-in. Upon arriving, I experienced a minute of worried uncertainty when no one answered the buzzer, but neighbors in the building were quick to notice and assist me, even letting me store my luggage in one of their apartments. And no sooner had I deposited my bags, when the "fill-in" keyholder arrived to save the day.
So what began as a potential problem was quickly resolved and serves to commend the owner's willingness to work with my schedule and the neighbors' unexpected and very gracious assistance.
What's more, my flight home had a late departure at 22:00, and despite the official check-out time, I was allowed to stay in the apartment until leaving for TXL at 19:30. Most generous and much appreciated. Service above and beyond the call of duty...