My girlfriend and I visited Javiers apartment for a city trip to Madrid. The apartment was perfectly clean and well equiped. Javier and his family were very kind and helpful. The location of the apartment is perfect, the apartment is located in the trendy district of Malasaña, with lots of nice restaurants and bars close by. Grand Vía is also around the corner, and from there it is only a short walk to the city centre.
Things to note:
If you are tall (I am 1.97m myself) you have to watch your head quite a lot when in the apartment. Especially the shower was a little uncomfortable due to my tallness, because I wasn't able to stand straight. My girlfriend had no problems in that regard.
Also be prepared to climb some stairs, as the apartment is on the top floor of a 5 story building. On the upside, the apartment is quiet and decently light during the day because of that, so we actually liked it this way.
Altogether, we had a very pleasant stay and would definitely recommend!