Great location, literally a block from Earl's court tube stop and lots of great restaurants nearby, a Boots across the street and an M&S marketplace. The stairs are a bit steep and narrow up to the room but not impossible or unusual at all.
Check in was very easy, but only because the cleaners had left the door unlocked! We had the wrong key in our lockbox but still got in because the door was open. The key situation was figured out quickly and resolved easily, fast communication from our host. We were happy to be able to get into the flat early as well, that was a big plus. We had trouble locking the door too but with messages from host it was figured out quickly as well, great communication.
It's a bit small for 3 guests, the futon was ok for sleeping, but the kitchen is very small, I didn't end up using it for anything other than beverages, but that's ok because we ate out almost all meals.
The room was lovely and clean, the bed was super comfortable, the temperature was good, the water in the shower very hot. Not a lot of space in the bathroom to set things, and we were missing a towel and a light was burned out but our host responded immediately with where to grab them from in the building.
Overall very good stay, only saying 4 stars because I wouldn't stay with 3 people again, but great for 2 guests.