Check-in was great, thanks to Marcelo's friend Alejandro who was the nicest guy. Explained everything to us, asked if we needed anything. (Gave my friend a new toothbrush as he lost his)
Marcelo sent me tips on the best bakeries, his favorite restaurants, (broken down by Spanish, Italian, Asian...), and even the best breakfast spot.
The apartment was sooo quiet, I got the best sleep you can imagine on extremely comfortable beds. You could not hear anything outside of the apartment.
Perfect location, friendly neighborhood.
I highly recommend renting Marcelo's flat if you are ever in the center of Madrid!