This apartment is wonderful, EXACTLY as advertised. It is generally very user friendly (we did have to ask some questions about the washer-dryer and the shower controls but either figured things out or our questions were answered very quickly) very clean and located in a very quiet neighborhood that is close to the Tube and local pubs, restaurants, etc. that make for a great AirBnB experience -- we truly saw ourselves living as locals!
One thing we did not enjoy was lugging all our suitcases up the very narrow staircase (all four flights!), a feature which I did not have ample warning of until I got to read reviews after I had already made the reservation. But that was a one time thing and going downstairs was much easier. :P.
Our luggage problem (we had 2 big suitcases) was quickly solved by our discovery of London's Airportr service which gave us worry-free transport to the airport while we enjoyed the rest of our hours before our flight. Not sure how this information can be used by your future guests, but it is a great service you might suggest to them, given the early checkout (10am) time at the apartment.
Overall a great experience which I would recommend to others, but warning them about the stairway.