Although we haven't met in person, Israel and Yolanda were really lovely hosts, always willing to help.
They made us feel welcome at their place, replied very quickly to all our questions, gave some great tips about what to visit in the city and what to do around. Might not be easy to find available parking spots in the neighborhood, but the big advantage is that it is free.
We stayed here for 1.5 months together with our dog, and the apartment had everything we needed for a long stay as well as some small parks around the flat (including a dog park) for our dog to play in.
During that time my girlfriend worked remotely, with no wifi connection problems, and the air conditioning was a big plus that made our accommodation comfortable in order to fight the high temperatures in Madrid over the summer.
It handles 4 people although might seem a bit cramped and dark in the common spaces since there isn't much sunlight in the living room, but on the other hand the mattresses are super comfy, and the kitchen has an exhaust fan that avoids accumulating smells.
The house is not located in the fanciest area of Madrid, was unfortunate to see so much garbage spread on the streets, but we always felt safe. Direct public transportations to the city center are 1min foot far, with several supermarkets (one 24h open), pharmacies, coffee shops, clothes stores, and hair salons in the area.
If you're thinking about traveling to Madrid, we recommend this flat!