We stayed for 6 nights at Maria's apartment and had a very pleasant time. The apartment is located on the ground floor of a beautifully renovated old apartment building, behind a very nice but busy cafe located in the same building, with windows facing into a quiet internal shared courtyard, with plenty of privacy. Although the apartment is behind a cafe, there is no noise when the windows are closed on the apartment. The other residents in the building are quiet and respectful.
The apartment itself is simple, clean, tidy, secure, quiet and with good privacy. Maria's instructions on how to gain entry were very clear and we had no trouble arriving, even though we were very tired from a long trip. The kitchen and bathroom are both very modern, and there was plenty of cutlery and cooking equipment. The bed was very comfortable.
The apartment is easy to get to, being close to both Friedrichstraße and Berlin Central train stations, as well as to multiple U-Bahn and tram stations. The area of Mitte where the apartment is located has clearly gentrified a lot in the last 5 years, with many new apartment buildings, restaurants, cafes and shops, and lots of young families. It is diverse, friendly, welcoming and safe. There is both a grocery store and a pharmacy located within one block, and there are a number of nice parks nearby with various opportunities for pleasant walks.
We only have two suggestions: 1) Some air conditioning would be good for summer. There was only a pedestal fan when we arrived and the weather was very hot, so the only effective way to cool the apartment was by opening the windows, which also let in some noise. 2) Updated instruction on wifi access would be helpful. The witten instructions in the apartment about the wifi appeared to be incorrect, as they referred to a wifi router that was located in a different part of the building, with a very weak signal that did not allow us proper internet access. We eventually discovered that the wifi router that we found located inside the apartment had a different username and password to that listed in the instructions. Once we deciphered this, and guessed the password, the internet was very fast. Others may not figure this out.
Overall, our stay at Maria's apartment was very positive and we would certainly stay there again.