The new bookstore is available on and off in France. So far, nothing new from other comments, but I like the ability to see only titles allowing coupons (I wasn't sure if it would be implemented in the French website), I miss the format of the ebook (epub ou PDF) and I dearly miss the choice to browse only free ebooks. Maybe it's somewhere, but I haven't found it yet.
I've always wanted a "cancel" option in the page you're at after pushing "buy", but I don't know if it's here or not due to the on and off appearance of the new bookstore. So far when I change my mind (all the codes have been redeemed, say), I can only go back by using the back arrow