Since I was arriving in Madrid very early in the morning, Javier was very accommodating and allowed me to check-in much earlier at 9:30am, which was very much appreciated! I was greeted by his cousin, who spoke English and answered all of my questions. He even walked with me to the nearest grocery store so that I could buy a few things, which was very nice of him.
The apartment itself accurately reflected the photos provided on the website. The WiFi and internet connection was very good, which was something I needed since I was attending conferences in Madrid and had to do some work. The neighborhood is nice and close to everything you need (i.e. Puerta de Toledo metro, tourist attractions, grocery store, etc.) and was relatively quiet (except for the partying and music on the weekend that lasted until 4:00am!).
The only hiccup during my stay was the day of the check-out, as there was a miscommunication on the part of Javier's cousin, who mistakenly advised him that I was checking-out at 9:00am, which was not the case. However, Javier was apologetic for the mistake and I was able to stay until the designated check-out time of 11:00am.
Overall, I was happy with my stay and I would recommend this place to anyone staying in Madrid for a few days!