The performances are great, but the screenplay doesn't hold together very well for me. Driver's character is almost completely lovable -- really, his only shortcoming seems to be that he's just too naive about what divorce entails. By the 10th time he gets blind-sided by something obvious, like the spouse "interviewing" all the most qualified lawyers in town to reduce his pool of potential representation, I could almost see why his apparent lack of basic insight might make him an impossible mate. It's totally unclear how he could possess the intellect needed to run a theater company and win a genius grant.
Johansson's character is almost completely unlikeable, IMO. She married a theater director and is surprised he wanted to stay with the troupe he founded in NYC instead of moving to LA to fulfill her TV dreams. She apparently refused to sleep with her husband for a year and couldn't wait to exact revenge when the young, good-looking theater director allowed himself to have sex with one of the hordes of young women lusting after him.
The couple never actually asks the child what he's going through, and he doesn't really ask them about what they're doing, either. He becomes whinier and whinier as they pass him back and forth and put on some kind of show about wanting to be there for him. In his defense, nothing they do with him looks like much fun for a little boy.
Baumbach's treatment of LA life is a stereotypical east-coaster's assessment, with multiple people randomly referring to all "the space" that supposedly exists in LA but not NYC. Having lived here most of my life, I don't remember anyone saying that. Ever.
I'd have preferred to see more of the struggle of the couple to try to make it work, rather than the many disjointed scenes involving attorneys. At one point, you think the story might just become watchable as a courtroom drama, pitting one strategy against another, but then that breaks down into nonsense, as well. In the end, you get a 45-second, "let's wrap this up" synopsis of how the negotiations went from Johannson's lawyer, the great Laura Dern.
I realize that I'm pretty much alone in hating this movie. That's okay. I have a feeling that it won't age well. Time will tell :)