The apartment is comfortable, for short stay. I stayed with my friend, we are both 60+. The bedroom upstairs is not suitable for anyone with any disability. It has a very steep stairs, and low ceiling. Would be dangerous in my opinion for small kids. My friend slept downstairs due to arthritic knees. You can walk to the centre of Biarritz in about 15mins, downhill all the way, . Steep uphill on the way back. Very nice friendly neighbours.
We enjoyed our time in Biarritz.