The flat is very well located, within walking distance of the old town and the Guggenheim. Despite the steep streets, we could do everything on foot (thanks to the help of the moving steps). For two or three people, the flat is certainly spacious enough. We parked our car for free in the surrounding streets (you have to drive around a bit to find a spot). If you want to swim or surf, you can take the car or metro to Sopelana. The only downside: because you are on the first floor, there is little daylight. Don't forget to ventilate well, otherwise it can smell a bit musty.
Carolina is a very good hostess, who is attentive and quick to respond.