While this is in the lively Malasaña area of Madrid, it's off the main streets so wasn't too loud at night. (However, I always travel with earplugs and would recommend these for light sleepers just in case!)
The apartment is small but cozy and really well-equipped - plenty of room for luggage / clothes and a little kitchen unit that has everything you might need if you're staying for a few days.
I was on my own - I don't know if it'd available for couples but for me it would be too cramped for more than one guest.
Jorge and his friend were very helpful and I would recommend this to anyone looking for an affordable, central stay in an interesting part of Madrid.