María Lyn's apartment is situated very conveniently in the centre of Madrid and all the important sights are within walking distance. It is quite loud on the street below at nights, although that wasn't really too much of a problem for me.
The room I had was large and comfortable.
I didn't meet María Lyn herself but her mother checked me in and was very lovely during my stay. I would recommend to anyone looking for a place to stay in Madrid centre who doesn't mind a bit of noise.