It was a great 6-nights stay. The location was very close to anywhere in Central London, and the neighborhood was classic, posh, and close to good restaurants and shopping places.
The flat provided basically all you need- a kitchen, living room, bathroom, with functioning heaters and a lift. Although the bathroom was a bit small, I expect the situation would be similar in these classic buildings/neighborhoods.
The host was also very supportive, nice and flexible. My family and I had a wonderful time there and leaving with good memories.