This is not a usual airbnb as it's run by a rental company. However, they were very friendly and quick to respond to an issue.
But only the basics were supplied. The kitchen was well equipped.

The place was in a great seaside location close to everything. It was a million dollar view! But the balcony is not so private with buildings (and works) close by.

The bed is very comfortable but the bedroom is a bit airless as there is no window only the en suite bathroom next door (also no window or fan). We needed to use a fan to circulate the air.

The water pressure was low.
There was nothing to hang the washing on.

Overall we had an enjoyable stay and its a nice place for a few days in San Sebastian.