I was in Berlin for a conference at Umbolt Universitat with 3 colleagues. The apartment has 4 bedrooms so it was nice to have our own personnal space each. It was also really clean and full equiped, which is always well appreciated. Its location was good; you have the U6 line about 5min from the apartment. It brings you in about 15 minutes to interesting places (museums, bars, restaurants...). Finally, we didn't met Helga, but her daughter who friendly indicated us nice places to go to enjoy Berlin. I definitely recommend it!