With my mum we spent 3 days in this apartment in Madrid and we had Carlos as our host. The apartment was clean, nice, just as at the photos, brightly decorated. Mum loved the interior a lot :)
It is well located: not in the very centre of city, but close enough to walk to the most of the places of interest (and you have metro just two minutes away).
You shouldn't expect much to see from the windows (they all face the courtyard), but for us it was not a problem as we spent most of the time in the city.
All in all it's a very plesant place to stay in Madrid which I would recommend.