Our overall experience was good. The flat is in a great location, easy transport to central London. We figured out how to have hot water from the tap. Simply turn it to cold and wait. ;) Big enough for 2 person. Kitchen was well equipped. I liked the view from the window.
There are a few things to consider. It is an old English building so the window is old and only a single glass in it therefore the traffic noise was loud for us. There are only electric heaters which has to be closed during the time you are out. So the flat is cold when you get back and takes time to heat it up. The shower had only lukewarm water for the first 4 days of our stay than later we had nice hot water. The oven was not working. This are nothing that would spoil your stay but is better to know.
I think it is a good value for money in London. The host was helpful and responsive.