Everything about this place is location. It is modern, reasonably clean and has all basic amenities. It is very, very small, but I guess it's to be expected in central London. It is a bit cramped for 4 people, especially if you have big luggage. I had to take out everything we use and put them out since we couldn't move with our luggage open. If you have experience staying at Airbnb in Tokyo, it is just about the same size and Tokyo is renowned for super small space.
We arrived early and the host was very gracious to let us check in early. My only issue is with the front door key which takes some skill to master when trying to turn it. Only one in our group of four mastered the technique eventually and he was our designated "key" person.
The apartment is just a 3-minute walk from Marylebone station, and there is a Tesco Express just around the corner. Cannot fault the location.
I usually tried to tidy up the apartment a bit before leaving, but having so little room to maneuver makes it very difficult to do any tidying up. Really sorry if we left a bit in a haste.