I went to see this Monday and it didn't end the way I thought it would. Unlike The Family Stone, it isn't predictable. I enjoyed the movie, but I imagine if you are having problems in your marriage, you might not want to see it with your spouse. As a primer for how not to conduct a relationship though, it is nonpareil!
Judy Davis plays an art gallery owner who is over-the-top, to say the least. She is Jennifer's boss. Judy could get an Oscar nomination for this role, and I would have preferred to see more of her on screen. Justin Long, who played Warren Cheswick on Ed, plays Christopher, the assistant at the gallery. His long hair and under-lip whiskers in this movie take him a long way from the nerd he played on TV, and while his role is small, it is notable.
If you go see this movie with no expectations of where the story leads, you will probably enjoy it.