Mary owns a superb flat - minimalistic and very stylish. It would be great, though, to have a shelf to store personal belongings, as far as a little stool might be not completely enough for two people to keep their things on. We didn't ask for additional storage though, as far as it wasn't an extra-critical issue for us.
Mary was very hospitable to share her kithen with us (to make some tea and sandwiches in the morning), and was all in all very friendly and helpfull host (we had a really inconvinient check-in and check-ou time)
Location of the flat is great too - just several steps from U-bahn station, Naturkunstmuseum, Berlin Wall Museum, all Mitte attractions, cafe's, etc. A big supermarket working till 23.00 is also about 50 meters from the flat.
We really enjoyed our stay and would deffinitely recommend Mary's flat to stay at.