What makes it is of course its rough and powerful voice (which is believed to have originated not entirely without means of consumption ;-)) and loose, free style singing. They seem to live the rhythm of her songs.
On their new album "Paris" accompanies a merciless good jazz big band, which fits exactly to make their own way in music.
Those looking for a good mood, perhaps like French chansons, and in general of the French language and culture is not averse is with "Paris" of Zaz have fun.