My stay was very nice. The apartment was spacious and roomy with everything I needed for my two days in San Sebastián. Everything is within walking distance and the beach is an easy walk. There are restaurants with Pinchos right out your door or you can walk to almost any street and find more places for dinner and drinks.
It would be helpful to have a guide book in the apt. Also be aware parking is either street parking which you need to ask the hours you need to pay or you can use underground parking garages nearby (there are 3 garages) but they are expensive $25Eur/day. There is apparently a free lot too about 30 min walk which is worth it if you stay longer.
The host was responsive and easy to work with when my plans changed and I came later than expected. I highly recommend this place and would stay again.