Alfredo's place is fantastic. In a fun, lively neighborhood, close enough to Plaza Mayor (10-15 minute walk).
The room is beautiful: it reminded me of a beach hotel. Everything was pristine and white and clean. I didn't have towels with me, and he readily provided those, along with shampoo and body wash (bring or buy your own conditioner, though). And the bathroom is spotless.
Alfredo himself was an absolute pleasure. I changed my reservation to leave a day early and he was more than gracious and helpful about making the change, and that morning he invited me to have coffee and breakfast with him and his mother, who is the sweetest lady.
A couple of (small) issues: the bedroom faces the street, so it can be a little noisy at night. I was exhausted so I slept through most of the noise but would recommend earplugs if you're a light sleeper. Given the location, room and host, it's a very small price to pay.
The second issue isn't a negative so much as an awareness: Alfredo speaks very little English. This was perfect for me because I was eager to practice as much as possible, and when I had trouble understanding him, he would type into google translate (which was really cute!). It's the perfect environment for people who want to be immersed completely, even at home.
Overall, I highly recommend staying here. As a traveler unfamiliar with Madrid, Alfredo was the perfect host to kick off my short stay. Gracias por todos, Alfredo!