I was mostly a solo traveler on my 10 night trip to Berlin. I felt safe and secure being alone, as this unit was off the street (I think all of MaCha's units are), and there were security codes to enter the buildings.
The apartment was comfortable and had a lot of character. I brought my web development work with me from California, and was able to be productive in the evenings. The internet was good, and the area was generally quiet. On Friday and Saturday nights, the restaurant downstairs tended to be a little bit noisy until about 1am, but nothing raucous.
So many cool museums, galleries, cafes, and shops were within walking distance! I was able to explore quite a bit during the day on foot. A grocery store was also available right across the square.
Hope to return!