I highly, highly recommend Alvaro's place to anyone visiting Madrid, whether for a short or long stay! The apartment is extremely spacious, modern, clean, and comfortable.
It faces an interior courtyard so you don't hear any noise at all from the street. I could occasionally hear some sounds from other apartments but all-in-all, it was very quiet.
The bed was very comfortable.
The water temperature and pressure were excellent.
There is a washing machine AND a fan in the bathroom to help vent out steam!
There is A/C in both the living room and the bedroom and it works beautifully and keeps the place very nice and cool, even in the height of summer when I was there.
The location is excellent, close to several metro lines and buses and in easy walking distance to Malasaña and Chueca, but removed enough to be much calmer and quieter. Plenty of bars, restaurants, grocery stores, and everything else you could need right in the surrounding neighborhood.
Communication with Alvaro was effortless, he always responded promptly.
I would definitely stay here again on future visits to Madrid!