Great apartment! It was exactly as advertised, very clean and located within easy walking distance of most sights. We were surrounded by great restaurants.
The Prado and other museums were about a 20 minute walk. The Palace and Cathedral about 10 minutes the other direction.
If your flight gets into Madrid early like ours did at 7 am, I recommend booking the apartment for the night before. Check in is at 3 pm. Carmen was very accommodating by letting us drop our bags before checkin.
Everything was lovely and we would stay here again.