This is a lovely and comfortable apartment and exactly as advertised--with the welcoming balcony overlooking a gorgeous courtyard. It's perfectly sized for a couple.
The historic building is very quiet, but the neighborhood around is lively and bustling. It is also less touristy than other more central areas, which is what we were seeking. A good grocery store (Supermercado MAS) is right across the street. Also close by we would recommend Il Rinconcillo for drinks & tapas, and La Quinta Brasseria for dinner, especially the delicious paella. Location is near Santa Catarina, which is to say, on the border of the eastern Santa Cruz and La Macarena quarters. The train station is also relatively close, but the Cathedral area is indeed a good 15-minute walk. The Prado San Sebastiano bus terminal and Maria Luisa Park are just over a 20-minute walk.
We got a warm and informative welcome from Miguel, which was greatly appreciated, since access to the building involves three or four keys (but fine once you get the hang of it). The kitchen is well appointed, and there's more space to spread out than we've found in other rentals. Very comfortable overall -- fine bed, terrfic shower, up-to-date windows and fixtures, washing machine, lots of storage.
We were very happy with it over all, and we know that where we stay makes up a big part of a holiday experience.