The apartment offered by Margrit and her family is absolutely lovely. Everything was clean, comfortable, and set up for convenience. My parents and I had a wonderful time and can't recommend this place enough.
I was a little worried about the location, but I didn't need to be: it is easy to reach the train station by foot and from there you are at Berlin Hbf in 13 minutes with the RE 3/4/5. We had dinner at three different fabulous restaurants within walking distance from the apartment. Overall, a great experience!