Carmen's place is in an ideal location in el barrio La Latina, lots of bars and cafes around, and just five minutes walking to get to Plaza Mayor, and another 5 or so to get to Puerta del Sol. We rarely needed to get a taxi, just late at night.
The air con in the apartment is excellent and it is in each room, one in the living room and one in each of the bedrooms. It was a heatwave of 40 degrees celsius when we where there so we definitely needed it! The bed are comfortable and the apartment is bright and airy.
The only issue is that it is hard to open the front door to the building, we tried a few different keys so the issue is with the building. However on first arrival we didn't know about this issue and so were outside the building for a while trying to get in, thinking we ay have the wrong key. So make sure you ask whoever checks you in to show you how to use the key. Only a small issue and definitely didn't impact on our stay.