Really great all around.
Very modern and clean flat. Location was fantastic with restaurants just feet from the apartment, and Old Town and the beach around a 7-10 minute walk.
The flat is on the 4th floor, but there is a lift which makes it easy. No air conditioning, but fans throughout the flat. Kids said the WIFI was excellent, and the download speed the best so far on our trip.
Checking in and out was simple. We loved San Sebastián and will be back, but next time for an extended period of time.