Matthias's place was perfect for our first stay in Berlin - great location, perfect amenities and very comfortable, clean & aesthetically pleasing.
It's situated in a quiet street in Mitte, walking distance from all types of attractions, as well as public transportation. It served as a warm basecamp for us during those cold winter days, everything we needed to know was documented in detail in a printed guide left for us by Matthias (including well-rounded personal recommendations & helpful tips), and his sister warmly welcomed us on time (which was pretty late at night, due to our flight getting delayed), showed us around & explained all we needed to know.
Both of them were very communicative & responsive throughout our entire stay (even though we had utter & complete privacy).
We'll definitely come back to celebrate one of our next anniversaries - thanks again Matthias!