PROS: Fantastic location. A stone's throw from Plaza de la Merced with several great bars/restaurants, and walking distance to all the main sites. Lovely check-in experience, very easy and they allowed me to arrive early which was really appreciated. Good digital TV including Netflix and Youtube connection. Good wifi, safe building. And a bottle of local wine in the apartment on arrival which was a nice touch.
CONS: Only small things, but the apartment wasn't quite fully stocked. No coffee maker or cafetière of any kind. No iron or ironing board that I could see, but maybe it was in the basement laundry which I didn't visit. A microwave would be helpful too, though not vital I suppose. The only other drawback was that there was no blind or shutter on one of the three windows in the studio space. This means that you will wake up whenever the sun comes up if you're a light sleeper like me.
If these small elements were changed, I'd happily give a five star rating. Good place to stay.