Perfect spot! Adrian's apartment is in a great location, right in Prenzlauer Berg. The area has a neighborhood feel and not as touristy, which is always a benefit for us! There are plenty of restaurants and shops in the area and you're only a 3 minute walk to a tram that will take you to city center within a few minutes! We never felt unsafe walking around the area, even really late at night.
The apartment itself is very nice and clean. It's very spacious and has a fully stocked kitchen. It is on the top floor (there is an elevator) and therefore the view from the balcony is amazing. The apartment also has a washer in the unit and the bed was comfortable.
We never got the chance to meet Adrian personally but communicating with him was not a problem. Before, during, and after our stay, he was always responsive and helpful. He had his friend check us in and show us the apartment and his friend was super nice, giving us suggestions for our stay.
We plan to be back in Berlin one day and when we do, I hope this apartment is available again!