We really enjoyed our stay at Max and Billie's flat! It was very clean, in a great location near transportation, and very easy to find. There are so many great coffee shops and restaurants all around the neighborhood and you're very close to Portobello Road and Kensington.
One thing to be aware of, is that the flat is at the top of roughly 5 or 6 flights of stairs and there isn't a lift. So if stairs are an issue for anyone in your party, this may not be the best fit for you. Again, we really enjoyed our stay so if you can manage the stairs you should definitely stay here!