Betty Blue's leads are naked about 50% of the time. There's no getting around that fact. If you find something deeply offensive about the human body, then there's no point in watching the movie.
But I will say that the film features the most honest sort of nudity. There's a weird sort of prudishness that suggests there's no reason to be naked except to touch and to feel other human bodies. The nudity of lovers is never just about sex; it's about being comfortable enough with another person that you don't have to wear your armor around them constantly.
Even Roger Ebert somehow can't see past Betty's boobs, which is a shame, as there's so much more to the movie.
Zorg, our brilliantly-named protagonist and jack-of-all-trades, takes up with a young firebrand prone to irrational bouts of fury. I won't spoil them for you, but it's amazing how quickly we turn from supporting her little rebellions to recoiling in horror from them.
Betty Blue's also an extremely funny film. Zorg's a great little comedian in his messed up world, miming at life while Betty excels at it.
The brilliance of the movie doesn't come from Betty's little tantrums, though (as witty as they are). The most superficial reading suggests that Betty's crazy and that's that. Really, she's symbolically fighting the steady encroachment of domesticity and the struggle to find her voice in a world where Voice is greeted with horror (it's no coincidence that each bout of craziness is set off by a new rejection of Zorg's long abandoned novel).
Eventually, even she forgets about Zorg's novel. There's no great moment of clarity or acceptance; life just keeps getting in the way. There's something incredibly true about that. We're not all broken by the abandonment of our ambitions; we just change.
The places change, the faces change, even the music changes. And that's easier for some than for others.
Betty Blue suggests that with each change, maybe we leave a small part of ourselves behind, until we're broken into jigsaw pieces, left desperate to make ourselves whole again. It's a depressing thought. It's not a happy movie.
You should see it anyway.