Very nice surroundings - but definitely far from everything if you rely on public transportation. Beach is great, but not much else to do with teenagers. Restaurants on the square are ok but not impressive. Small convenient market on the square. Use the Carrefour 10 min walk away for better prices.
We took the boat to Spain a few times. Much nicer there for dinner. The boat is great and in seven minutes you are on the other side for wonderful tapas. Show up 20 min before departure at peek times.
Public transportation is really bad. Busses are few and very far apart which makes it a very difficult to go anywhere. Connections between It is easy to feel stuck in a small beach resort. To go to San Sebastián take the little boat and bus E21. Worth the trip. Great town.
All in all a very nice, small, sleepy beach town where 3 days are fine - and more than that a bit challenging unless you are there for the water and reading books.