Overall: excellent.
We stayed with our kid for a week in London and this was our first time we used Airbnb.
Location, location, location. The flat is close to Buckingham, Westminster, Piccadilly, theaters, parks and between 2 tube stations.
Francesco was very flexible with check in/out which helped us a lot. The flat was clean and spacious, equipped with everything we just needed, perfect for a family trip.