It would be lazy, but not really inaccurate to describe this as a modern-day French version of "All About Eve". It has a lot more sex (I said it's French) and kind of a bisexual twist (it's modern-day French). The story involves the young fan (Isilde LeBosco)of a pop star diva (Emmanuelle Seigner) who finds her way into the inner circle of her idol, but manages to sow a lot of discord by becoming involved with the idol's jackass boyfriend as well as inciting a no small amount of inter-generational lust in the idol herself. . .
Emmanuelle Seigner is perhaps MOST famous for being Mrs. Roman Polanski, and she has really done her best work in her husband's movies like "Bitter Moon" and "The Ninth Gate". She's not a GREAT actress, but she's always been a sexy and fearless performer. She seems a little long in the tooth to be a "teen idol", but, hey, she's a lot younger than Madonna. Isilde LeBesco seems to be a rather ordinary-looking girl, but she also possesses a hot little body which she has been showing off in French movies since she was the French-version of barely legal (I suspect Seigner probably had to keep her nubile co-star here away from her notorious husband). Seriously, LeBeco is also a very decent actress, and this movie is really both a classy French dramatic thriller AND a pretty hot inter-generational, bisexual sex romp. But if you prefer the former, I'd also recommend the similar French film "Love Crime", and if you prefer the latter, I'd recommend the film "Nathalie" with the other French Emmanuelle, Emmanuelle Beart (which was recently re-made as Canadian/US co-production "Chloe").
As for THIS film though, it's not "All About Eve", but it's certainly not a waste of time either.