The flat is really nice. It is specially cool because you'll have the chance to be hosted in a traditional building in the center of Bayonne. Also if you come by car, you have very near the parking La porte d'Espagne, for which you only pay from 9h to 19h about 1€/4h.
The only pitfalls are the toilette, which takes several hours to refill, and the bedroom window, which is very old and you can hear everytime someone uses the community stairs. In our case this wasn't a problem since nobody used the stairs from 12am to 8am, or we didn't notice.