The interior is nothing to get excited about (sort of feels like you're eating in a hotel or office building lobby). Plus, the staff were very cranky on the day we went in and they were not busy at all, so, not sure what that was about (generally unfriendly, lackluster).
However, the food is really quite good - fresh ingredients, good ingredient options (some crepe places are quite boring, I've noticed), and all made quickly and at a fair price. Hazelnuts provides a nice opportunity to grab a good quality breakfast and go eat it outside in one of the fantastic nearby parks for an excellent view of the city.