Definitely one of the best apartments we've ever been.
It's elegant and furnished with good taste, as shown in the pictures.
The kitchen is well equipped, with 1st quality appliances.
The bathroom is large, with an extremely convenient washing/drying machine (which we used during our 5-days stay in August).
Communication with the landlords was very easy, with prompt replies and suggestions.
One evening we had a minor problem in the bathroom, and it was fixed in less than an hour! Excellent service, very very much appreciated.
The location is suitable for a 10 to 20 minutes walk to the three main museums (Reina Sofia, Prado and Thyssen-Bornemisza).
Nevertheless, a metro station is across the street, for those who want to use the public transport.
I unquestionably suggest this apartment.