Just got back from a wonderful stay in London. We stayed at Tobias and Annette's flat and couldn't be more pleased with it. The location is perfect- near the tube, grocery stores, and restaurants, but on a quiet residential street. I doubt you could find something this convenient at this reasonable of a price anywhere else.
The flat is neat and small- perfect for a couple or very close friends/family. Some of the appliances took a little trial and error on our part but the manuals are available in the flat. Make sure to bring outlet converters if you're coming from the U.S. Also please note that the flat is up two flights of stairs so it's better if you pack light and aren't carrying a steamer trunk with you or something.
Tobias and Annette were considerate hosts and very easy to communicate with. I would recommend their flat without reservation.