Maria Jesus's apartment is delightful - spacious, very clean, nicely decorated, quiet and conveniently located (a few minutes' walk to the subway or a bus line to the center of Madrid). She met me at the apartment, showed me around it without rushing, explained everything to me, and gave me helpful hints about supermarkets, a wonderful roasted chicken place, the bus line. She's very personable. Although only a friend and I stayed there, four people can stay there very comfortably with the two bedrooms with queen size beds and, in fact, there's also another bed in the pull-out sofa in the living room.
The only drawback, which I don't consider a dealbreaker, is that the apartment is on the third floor without an elevator.
I highly recommend this apartment.