The host, Matias, is very responsive and kind - before, during, and after my stay.
The place: Apartment is up one flight of indoor stairs. The interior stairwell is very dark at night, so bring a light and be careful on the steps.
The front door locks very securely. I felt very safe.
Check-in was easy. I met the cleaning staff, who gave me the keys and showed me around. She spoke Spanish only, and was very friendly and helpful.
Everything was clean, comfortable, and simple.
Amenities:
The apartment has lots of light, good ventilation, and several small balconies that overlook the bustling neighborhood streets.
Washing machine, and a drying rack (which I put on a balcony). The apartment gets lots of sun, so things dried really fast!
Internet was very fast.
The water in the shower was VERY hot (this is a good thing, but be careful)! Host provided clean towels and some basic shampoo/soap. There are shops nearby to buy anything else you need, but international brands are hard to find in Madrid, so bring your own if you have a preference.
The kitchen is very small, but has everything you need for one or two people. There is a water kettle, microwave, toaster, stove, and fridge/freezer that all worked great. The knives could be sharpened. :)
Host provided cleaning supplies under the kitchen sink, which was nice for a longer stay (broom/dustpan, microfibre cloths, mop, laundry soap, dish soap, floor cleaner, glass spray). I really appreciate this because I do not like to leave a mess in someone's home!
The bed was very firm and comfortable. There was a lot of space to hang clothes, and extra drawers.
The air conditioner worked very well in the living room and bedroom, though the weather was very nice so I just opened the balcony windows.
The location cannot be beat. It's within walking distance (under 20 minutes) to everything I wanted to see in Madrid, and very close to a Metro station.