I was in San Sebastián to run a marathon, Sonia’s place was in the perfect location for that as I was only 100 meters from the start and finish ! However I should have paid more attention to the surroundings because the flat is directly above a bar / nightclub and I could hear music until 4am which isn’t very practical the night before running 42km. But for someone looking for night life, being in the center of the city close to restaurants and the historic downtown this place is perfect.
Or if you don’t mind a little noise go for it ! Sonia is a great host and I still enjoyed my stay, the error was more mine in not realizing the surroundings !