Nicolas and his sister Nina were very friendly, responded very fastly to all our queries. We stayed at their apartment during 3 days in Jan. The location is perfect (subway, supermercado, restoraunts, bus stations etc are really close). The apartment is very big and comfortable. I would recommend this place for everyone: shortstay tourists and longstay business people.
So the only small negative are: the main bedroom is a little bit noisy in the morning and hot as there is no A/C there. No TV.