I had a wonderful stay at Rosina's. Her apartment is in a residential neighborhood, but still close to Potsdamer Platz (10-12 minute walk). I stayed here mostly because I was going to two concerts at the Philharmonie - it is literally 4 minutes away on foot!
I also appreciated that the room was very bright with lots of sunlight and had a desk and a full-length mirror. Rosina and her family were very respectful of my privacy.
I hope to stay again! Oh, and her little daughter is simply adorable!