We stayed in Louisa's apartment as a party of 2 for 10 days at the end of 2017/beginning of 2018.
We found the location great: close to 3 tram lines and 1 U-Bahn line providing easy connections to all places of interest; lots of supermarkets, groceries , cafés and restaurants; the weekly market on Köllwitzplatz a few minutes away. And we like the surroundings of Prenzlauer Berg, the apartment being just in the middle of this pleasant part of Berlin.
We rented only a part of the apartment (1 bedroom + living room + kitchen & bathroom). The bedroom was quiet. Kitchen and living room look onto a busy street, but in winter with closed windows this was not a concern for us, and these rooms are bright because they have an open outlook.
The apartment has a very personal touch, it is not at all like the standardised professional rentals which are now commonplace in Berlin since the new stricter regulation for temporary rentals. The photos on the site are accurate and show how attractive it is. Rooms are spacious and the ceiling is high. Note that the apartment is on the 2nd floor (2 levels above street level) : there is a lift but it only serves half-floors, so you will have to carry your luggage on the equivalent of 1 floor.
We appreciated the possibility to check-in early. We regretted the lack of space to store our things - not a single cupboard or drawer had been reserved and we had clothes for 10 days. We also regretted the untidyness and uncleanliness.
Communication with our host Louisa was efficient if not proactive. Besides, this was not our first visit to Berlin and we speak German so we did not need particular care or tips about the city.
To sum it up, a very recommendable appartment.