I think this is a typical French author movie (read: pleases only its author :) where part of the audience will walk out, part will stay totally annoyed, and some will love it thinking it's of the greatest insight, overall not generating much revenue.
Plot: A small troupe of Franco-Italian actors present a new theater piece in Paris, with moderate success. Off scene, we follow the lead French actress and the Italian director who are married. She hooks up with her ex, he searches for a manuscript and the story develops from there...
There is no plot per say, but rather a microcosm of people floating in a fish tank: it's a study of characters. I guess the movie is about relationships and 'love'. A few things annoyed me, there are quite a few actors who act really bad (ie they act as if at a theater, with voice intonation and expression of feelings totally off). There is some sort of mini action going on, but nothing leads to anything. There is a few spots where the action is absurd (characters attach to each other artificially act or find things or change behavior the same way). The end is totally stupid (IMHO) because the state of some of the characters is unfinished.
The few things I liked are the women attraction: the younger one is very attractive, the actress and dancer are too, though it's partly because of their awkward detached personalities. I've been told the guys are unremarkable, sorry ladies :)
Overall it might have been OK as a simple theater piece but as a movie it's quite boring and condescendent.