My friend and I had an enjoyable stay at this apartment. It is in the Gros neighborhood of San Sebastian/Donostia, which was less touristy than the old section of the city (the Casco Viejo area). Of course, the touristy areas are where tourists inevitably want to go, so you will find yourself walking (or taking taxis/buses) quite a lot from this location. San Sebastian is spread out over a very large area so it is good for walkers.
The apartment was quite comfortable and the 2 larger bedrooms are very separate from each other, so 2 people (or 2 couples) sharing the apartment will have good privacy. The space was very clean and well organized, and we had everything we needed during our stay here.
The best feature of this apartment, in my opinion, is the host himself. J Miguel was very accommodating and helpful to us when we arrived, and he is very attentive to all the details. He clearly cares a lot about the apartment and takes his hosting role very seriously, which I find quite appealing!
If you stay here, one positive is that you are very close to the coastal hiking trail from San Sebastian to Pasaia. If you are fit and enjoy a walk in beautiful natural surroundings you should not fail to take this hike. It is somewhat demanding, especially the part leaving San Sebastian which goes up very steeply, but overall it is not too difficult and the scenery is quite beautiful. You don't even need special hiking boots to do it -- but don't wear sandals, either. If you prefer to stick to pavement, you will get quite a good long walk going all the way to the Peigne de Viento on the other end of San Sebastian.
There is a good moderately priced restaurant not too far away -- Tedone. It is mostly vegetarian but does have fish as well. It is on a rather spooky small street, and the space is rather strange, but I thought the food was good and good value, with friendly service.