As I have the benefit and advantage of speaking a little bit of German, I communicated with the hosts the entire time in German. Whether I sent messages within airb&b or mobile text messages, they answered promptly. In turn, I made sure I replied in time, too.
Very spacious for one person, the apartment comes with lots of storage space, and I think the apartment is ideal for two people. I had no issues with any of the furnishings in the apartment; the only thing "missing" was a laundry-/washer-machine (which I didn't really need). Having amenities like the coffee maker, the water kettle, and toaster made my mornings go very easy. One minor detail missing in the kitchen was a small scrubber which I bought on the cheap to go along with groceries' shopping at the Edeka store nearby. The electric recliner chair and electric adjustable bed were huge bonuses which made the end of long busy days on foot in the city very comfortable indeed.
The apartment location is superbly ideal because (1) it's very close to a U-Bahn station, (2) it's just a little bit farther to an S-Bahn station, (3) it's in a neighbourhood/borough which I prefer to stay while I'm in Berlin, and (4) it's close to a large grocery store, banks, and Imbiss and Späti shops. Because I've visited Berlin countless times before, I didn't need pointers about what to do; I had already planned a "spreadsheet" full of things I needed to cover during my week-long stay. In choosing this apartment, my prime concerns were easy access to U-/S-Bahn and available services in the immediate area. What ended up happening was that I immediately made this apartment and neighbourhood feel like "Zuhause" ("home").
I would very much like to recommend this apartment, and I'm seriously considering returning to this apartment (if available) when I'm back in Berlin in the near future.