Vanessa Paradis is most famous today as American superstar Johnny Depp's longtime girlfriend, but she is also a FRENCH actress, which means she, of course, she has an early role where she plays a nubile teen in love with a middle-aged man. The French penchant for drooling over beautiful teenage girls may be annoying to some, but is it really worse than the American/Hollywood penchant for pretending they're NOT drooling over the beautiful teenage girls that seem to find their way into every other movie somewhere? But really there is no "eew" factor here--there are no on-camera sex scenes between the man and the girl, and 17 or not, a few shots of a naked Vanessa Paradis are not going to make ANYONE go "eew".
The bigger problem with these French "lolita" movies is the plausibility. Middle-age men don't generally date teenage girls, not because they find them icky and physically unappealing, but because they're very rarely as worldly and sophisticated as the fictional nymphets in these French movies. Moreover, even in France very few girls that age are probably too interested in ennui-filled men old enough to be their spry young grandfathers. It's actually understandable that the married middle-aged philosophy teacher in this movie would fall in love with his brilliant but troubled student since she is absolutely beautiful (clothed and unclothed) and wise beyond her years. But Paradis' character is supposed to be this streetwise urchin who has dabbled in prostitution in the past, and it is a little hard to believe she'd fall madly, obsessively in love with a fifty year man just because he shows her some kindness. (Also, while 17 may not get you twenty in a French bastile, I'm pretty sure it would get you kicked out of the teaching profession).
Paradis is indeed pretty good in this (although she would be better playing another troubled teenager a few years later in "Elisa"). And this movie is definitely well-made with some memorable scenes of sad beauty. It still remains somewhat of a middle-age male sex fantasy however, which doesn't make it at all distasteful, but does make it somewhat implausible.