We are a family of 5 with kids ages 9, 6, and 4. We had a wonderful experience. Our hosts were very professional and even organized a van taxi transfer from and to the airport for $40 each (we gave $5 tip each way as our driver was super helpful).
The apartment is just what the photos and previous reviews described, no surprises, very usable and functional. Certainly not luxurious by 4-5 star hotel standards, but roomier and much more usable (great new Bosch washer!) and charming (location, location, location!) than the expensive luxury hotels we stayed at before. Loved that little street and neighborhood! Only downside was some noise in the morning due to construction in the building, but super quit at night. We were worried about the summer heat in Madrid, but AC worked great in the apartment; and the fact that there is few windows/ no views is somewhat offset by less street noise and less heat.
Overall a great experience, hosts were super indeed! - Jens & Sherry