Anna's place was extremely comfortable for our group of four women. If anything, it was even BIGGER than we expected and we felt like we had a lot of space to spread out and not be in one another's way. We had everything we needed in the kitchen, beds were comfortable and with nice clean linens and clean towels. We were well located in Mitte close to the Berlin Wall memorial, Friedrichstadt Palast, a lot of restaurants, public transportation, quick easy shopping, etc. Anna was a lovely hostess and the apartment was very clean.
Things to note:
There was an elevator that went to the "half Floor" in between floors so you still have to walk up some stairs (two "half flights") if mobility is an issue for you.
Non European travelers - For the most part, older places in Europe do not have any AirCon if it is hot outside. It was quite warm while we were there, but Berlin cooled off at night time and we could open the windows to make the flat comfortable.