My group of friends rented Joaquin's place in Madrid for New Year stay. It was well designed place for 6 of us - 3 full bedrooms with separate bathrooms, and a separate living room. The set up of the place is really great.
The apartment itself is brand new, recently renovated. Though I missed some personal touch, it was a bit too sterile. The apartment is made for rentals only, managed through agency, so it is not your real airbnb experience.
The ventilation and draining system in one of the bedrooms did not function properly, so we experienced some discomfort of bad smell. Also had an issue of small flooding in the same bathroom.
The neighbourhood is great, full of restaurants and major tourist attractions close by. There was quite some noice from the street though, especially in early mornings.
Overall would really recommend Joaquin's place for a larger group, also if you prefer to stay in the center as you can easily access many great restaurant and sights. The place is clean, well designed; the host and the managing agency were easy to reach. The benefits of the apartment outweigh the inconvenience we experienced and we would not hesitate to stay there on future trips to this wonderful city!