Others have previously mentioned outside noise & being able to hear the underground under the apartment.
Firstly, you are in central London so you can't not except to hear some sirens and traffic noise but this was almost impossible to hear except when you are in the apartment without any music, TV or fan on and certainly wasn't intrusive or enough to disturb in anyway. As for the underground, again yes, this can be heard but is very distant and not enough to bother you so please don't be put off by either comment previously.
We were met outside at the agreed time by somebody appointed to the owner. I don't think he'd been to the apartment before but showed us the way and ensured all was in order before leaving.
Apartment was immaculately clean and just as pictured. Finished and furnished to a high standard and with toiletries and towels provided it saved for the need to jack extras when travelling.
The apartment is really well situated just a 3-4 minute from South Kensington underground station and a bus stop directly outside too. Good choice of restaurants, pubs and coffee shops all just a few minutes away.
As a family of 4, (2 daughters 15 & 8), we used the apartment for a few days to visit Buckingham Palace, see a London show, visit Oxford street and also the London Eye and the position made visiting an ease and the apartment is a great size - not like some central London pokey apartments!
Would definitely use again and would not fail to recommend staying here.