We stayed for 2 nights. Check in was very easy, and the hosts even let us drop our bags off early so we didnt need to traipse around London with luggage.
The place was very clean and not at all noisy (other than the usual traffic noise but that is to be expected for London - and even that wasnt even that loud and you couldn't hear anything after a certain time).
The flat can get a little bit cold, but the heaters provided were suitable and warmed the flat up relatively quickly.
The only recommendation I would make is to, if possible, provide two key's to the flat rather than the one, just in case any guests wanted to return to the flat alone or something while other guests in the same flat stayed out. This is only a minor thing though and didnt impact our stay in any way.
Overall a very positive experience and stay. We would definitely return.