We had a very pleasant stay at Pilars flat. It is very clean and modern, and very well situated for both sight-seeing, restaurants and shopping, making it a good option if you for some reason want to reduce excessive walking.
It is situated in a pedestrian area, so if you come by taxi I suggest you get off at Las Setas or Plaza del Salvador.
Air condition works perfectly, which is fine since it is the only way to refresh the air since there are only windows to one side of the flat (to the courtyard).
I recommend this flat, especially for a small family.