I spent a couple of days with my best girl friends for my 30th birthday. It was my very first time in Biarritz.
Alexandra - and Fred - has(ve) been really helpful : we had plenty of recommandations in terms of restaurants and wine bars (I highly recommend 'Les contrebandiers' next to Les Halles in the old part of the city center)
The flat is located in a quiet courtyard, very close to everything you need (grocery shop, cheese and wine shop, bakery...), and 15/20min far from the city center.

The flat itself is as described : it might not be very roomy but it was exactly what we needed. We had enough beds for every one (even a spare one), a very functional kitchen with a dish-washer, a nice veranda and terrasse where you can have breakfast/lunch, and a super clean bathroom with an amazing shower.
I recommend !