We had a wonderful 5-night stay in Begona's sweet apartment. It is cozy but well laid out with a comfortable bed, great shower, and large kitchen. There was plenty of storage space for our clothes and everything else we were hauling for a 2-month trip. We parked our car in the provided spot right next to the apartment and never moved it for 5 days.
The terrace and views of San Sebastian are terrific. We had the good fortune to see the city's "Great Week" fireworks two nights in a row from the terrace, and they were spectacular. The hill leading to the apartment is as others described it; definitely not for the faint of heart or anyone with mobility issues. The walk to the Old Town was longer than we'd expected, but we took that as a bonus as we got in lots of steps to counteract all of the fabulous food we ate in San Sebastian.
What really makes this place special is Begona. She is the sweetest lady and is very focused on her guests' comfort and well being. She lives upstairs and we hardly heard her at all.