Christina was very welcoming and provided a written guide to Madrid, neighboring cities, and the local neighborhoods. Although we didn't meet her when we arrived (her sister Carmen let us in), she was always available via text or the AirBnb App. We liked that we were met by Carmen within 5 minutes of arriving and that both Carmen and Christina spoke English.
The home is nice and as advertised. We liked the washing machine and AC especially as it was 105 degrees when we were in Madrid. The place was very clean and we got the impression that no one is permanently living there and it is only rented out to guests, which was nice as we didn't feel like we were intruding on someone's home.
Regarding the location, as a few reviewers have commented, we did hear the bar downstairs at night, but it wasn't loud enough to bother us and we had no problems sleeping. The apartment is very close to the Metro and on a line that is very convenient to get to many desirable places in Madrid. There is also a nice cafe 2 blocks away that we went to for breakfast several times. There are also many restaurants within walking distance. The neighborhood seemed very safe to us as well.
The only downside was that the key to the downstairs entry door did not work so well (sometimes it took 1-2 minutes of trying before we got the lock to turn and door to open). But we were always able to open the door so it wasn't a big problem for us.
Overall it was a great stay and if we were back in Madrid we would absolutely consider staying there again.