We stayed in the apartment for 3 nights in January and enjoyed it a lot. Perfect location within the city, we only needed public transport to get there from the airport and back (takes approximately 1:10h with two changes). For the rest of the time we were just walking around city center, no need for taxi or other transport, all interesting touristic points can be reached by foot.
The apartment looks exactly as in the photographs. We met both Victoria and Carlos in person, very nice and helpful both of them.
Just one detail - the temperatures in Madrid are quite low in January and the apartment has no central heating but there is air condition so you can heat the room with it. I'm sure that this is an issue only during few weeks in a year as Madrid is known rather for fine, hot or super hot temperatures :-).
In general we were very happy with this accommodation and I would use it again in the future without hesitation.