We enjoyed our stay in this apartment. It was bigger than I had expected it; it has actually three beds (one double, and two single) which is extremely handy if you travel with family or friends. The kitchen was well equipped with dishes, dishwasher, toaster and coffee machine. The heating works perfectly, and the windows are well isolated - we did not really hear any noise from outside.
The location as such is great. St. Pauls and many tube stations are in convenient walking distance and there is a small supermarket nearby. Check-in and all communication with Rolf and Mok was totally easy. They answered quickly to messages and where extremely helpful when questions or problems occured.
The only point that I could make is that we were informed quite late that the elevator is not working. As one of my guest has problems with stairs, this was inconvenient. However, I would definitely recommend to stay in this apartment when in London, given its size and perfect location.