I couldn't have been happier with the stay. The hosts are very nice and accommodating people. In my case my flight got in very late and they had no problems with my late check in.
My room was very spacious with a very comfortable bed, large TV, and backyard access. Complimentary breakfast is a nice touch and honestly adds much warmth. London is very spread out, though fortunately this apartment is right by three metro lines and a central railroad stop allowing relatively quick and easy access to the city center.
I definitely recommend you stay here if you find yourself in London :).