Me and my boyfriend's stay at Montse's apartment was great! The place was very clean and modern. It was a light and fresh apartment with the possibility to close the blinds (good ones) if you are sensitive to light when you're sleeping, and we appreciated having an AC in the bedroom since it was so hot outside. Additionally, the location was perfect, only 10-15 minutes walking distance from Puerta del Sol. We walked everywhere and never used any public transportation, except to and from the airport/bus station.
Furthermore, Montse was a very helpful and nice host. She was quick to reply and gave us some great recommendations of restaurants and things to do. A fantastic host in every respect! Unfortunately we never got to meet her since she was abroad while we were in Madrid.
Moreover, we shared the apartment with Montse's flatmate Yuko, whom we barely met. She was very quick to lock herself into her bedroom as soon as she got home, so we only got a glimpse of her a few times. We never really understood if it was a gesture of respect for our privacy or if she just didn't want to bump into us. Either way we thought some communication would have been useful in order for us to better coordinate the use of the kitchen and bathroom. Sometimes we were worried that we used the shared spaces when she needed them.
All in all it is an accommodation that we would definitely recommend!