The apartment is really well placed, right in the center of Biarritz. So you can do everything by foot. In August, when we were, it sometimes got a bit noisy, but that is not the fault of the apartment, but rather of Biarritz being quite a tourist town from mid-July to mid-August.
Also, the beaches are very close. You can jump into the water before having a petit déjeuner in the city centre.
The apartment is SUPER well equipped. It was great to go shopping in Les Halles (2min away by foot) and cook our own dinner with the local specialities. And for that the kitchen is really great.
Finally, the host as well as the concierge are really nice. They are very fast to respond and help you with anything.
So, I would totally recommend to rent this appartment. I don't think you can get any better in Biarritz.