We spent three nights at Olivier and Sophie's apartment ! Conversation was very smooth with them and their flat is located in a perfect location, quiet street in city center close to every spot you want to reach (beach, restaurant, bars...) and a very nice terrace !!!!
I highly recommend this apartment for you stay in Biarritz, it is nice to see that there are still true AirBnB experiences when you go to someone's and when you feel the place is inhabited and not a commercial business as you can find sometimes !
Thanks again guys we spent 4 awesome days!