We stayed for three nights and it was a perfect amount of time.
The apartment is very tiny and so is the room, luckily we didn't have too much stuff with us and we were lucky to also have access to a nice little balcony.
Good kitchen appliances, however you could only use one at a time because there's only one socket.
The flat is in a pretty decent neighborhood as far as we could tell and there's very easy connection to the city.
The only flaw was that when we arrived, the floor was quite dirty with crumbs and street dirt and the desk drawers were also a bit gross with weird spots and a few strands of hair in them - since there is a cleaning fee, we would have expected it to be a bit more clean.
Also, the walls are very thin (inside the apartment and towards the next one too), so we were awakened by roommates getting up very early two days in a row and kept awake by a running washing machine the last night.
Apart from that, everything was awesome tho.
They were very fast to reply to messages and answer all questions.
Also, the self-check-in was explained in detail and thus extremely uncomplicated and easy.
All in all, this AirBnb is definitely a good option for getting to spend a few nights in London on a tight budget!