Sylvia (José's friend) greeted us as soon as we arrived in London, even if it was four hours before check-in. The apartment wasn't ready yet (obviously, since check-out is at 10 and a good cleaning up requires some time), but she allowed us to leave our luggage and begin our visit asap.
She was very friendly and thoughtful. I visited London many times so I didn't need much help, but I'm sure she would be just as helpful with someone who doesn't know the city as she's been with us.
The apartment itself was great, smart, spacious and in a nice, quiet area (even if it's just a few minutes walking distance from Camdentown).
The only teeny-weeny thing that surprised us was that there were just three hand towels plus a bath towel. Luckily, we had our own bath towels, so it was fine. Also, when we arrived there was not even a single roll of toilet paper, but a huge Sainsbury's is only a couple minutes away from the apartment, and we had to do the grocery shopping anyway.

It's been a wonderful stay, I will totally recomment the flat!