Katarina's apartment was a great landing place as I moved to Berlin with my family for professional reasons. We rented it for a couple of months while looking for a more permanent and unfurnished place. It's location is hard to beat: very central, across the street from the Mall of Berlin, close to many restaurants, a few blocks away from Potsdamer Platz... The apartment was also well equipped and the living room had charming mid-century furniture.
There were some evenings in which events held in the Mall of Berlin were a bit too noisy, but never for very long. We also had some trouble with mosquitos during the night and had to wear repellant in order not the have our sleep disturbed. As the apartment had only one set of bed sheets and towels for each of us, we had to buy extra sets, so we could have substitutes while washing and drying the original ones.
All in all we had a positive experience during our stay. Katarina is a very responsive host and was willing to accommodate our successive extension requests, as we kept on trying to find an apartment to rent.