The flat is in a perfect location - within walking distance of the Casco Viejo and in the heart of a quiet and pretty shopping district.
The apartment is gorgeous and fuctional (the building is impressive). You can tell the flat has been recently renovated. We were just two people and one was working remotely, so the 2nd bedroom was used as an office. Wi-fi speed was good for multiple long Zoom calls.
Asier was very helpful and even let us check out late to catch our late night flight back home.
The only thing I think could be improved is having some supplies that tourists are unlikely to buy on holiday (such as salt, oil, and spices for cooking). Cooking while on holiday in San Sebastian is probably not high up on anyone's priority list, but in our case we were there for a week and it would have come to great use. Still, this a minor thing that doesn't take from all the positives but would be a cheap way of giving people a better experience.
Eskerrik asko, Asier!