Expect a tidy home with all the facilities in the world.
Parking is free and, though it might be tricky to find, it is right by the house and feels safe.
Also expect a somewhat impersonal experience, where you share everything with around 5 to 8 other guests. That includes 1 bathroom for all those guests.
We had an unfortunate experience where we needed to leave the house early next day so we came back from the city with ample time. We had to wait an hour for 4 other guests to finish up before being able to use the bathroom! The bathroom is actually our least favorite part. There is no active ventilation and no windows. After waiting for all other guests to finish up, you're left with a dampy moist bathroom with a mix of unwanted smells. Also there is mold on the ceiling above the shower and sink (no wonder with the damp).
That's not to say the house is not clean. The room was very nice and impecablly cleaned. So were all the shared spaces including the bathroom.
Location is about half an hour by foot to see anything, which is not too bad. The walk is quite nice. It is also connected by bus (fare under 2 euros).
All in all I'd say it's a bit overpriced for the experience (you pay for all the shared facilities whether you use them or not), but not bad for a short stay in the beautiful San Sebastian.