We stayed at Alain's place for four nights. The apartment was located in the centre of Madrid and (almost) everything was within walking distance, and for the things that weren't, there was a metro station close by. As for the place itself, it had everything that we needed. The shower wasn't ideal because the temperature could fluctuate from steaming hot to icy cold, no matter at what temperature it was set. Also, the shower was relatively small but it sufficed.
Also, the neighbouring building was under construction, which could cause a lot of noise from 8 a.m. onwards and the bar located next to the building could also cause a lot of noise.
Furthermore, we were welcomed by Nolasco, who was very friendly and welcoming. However, communication wasn't perfect because they barely spoke English. But, with the help of Google Translate, it all worked out and he really did try to communicate with us.
Overall, we enjoyed our stay and especially the location of the Airbnb was perfect. The apartment could use a little more ambience because there was little to no decoration, but that is not really an issue worth mentioning. Definitely would recommend and would stay at this place again!