A tale of personal accountability and how life isn't always fair but that there are some things you can rely on. Like the younger brother who always screws up, and the older sister who is always on his case, but also that people can and do sometimes act out of character or even change, and that some bonds are too strong to be broken.
It is a curious morality tale in which even Ron (played by the director, Kenneth Lonergan), the local priest admits that it doesn't matter too much about what you call your beliefs as long as you just have something to believe in:
Sammy: I don't know what the church's official position is on fornication and adultery these days, and I felt really hypocritical not saying anything to you about it before, but what is the official position these days?
Ron: Well... it's a sin.
Sammy: Good, I think it should be!
Ron: But we try not to focus on that aspect right off the bat.
Sammy: Why not? I think you should.
Sammy: Maybe it was better when they screamed at you from the box for having sex with your married boss, they told you what a terrible thing it was, they were really mean to you. Maybe it would be better if you just told me that I'm endangering my immortal soul and that if I don't stop, I'm gonna burn in hell. Don't you ever think that?
Ron: No, not really.
Laura Linney (as Sammy) and Mark Ruffalo (as her brother, Terry) carry the movie. Matthew Broderick (as Sammy's boss, Brian) does enough to show you why no one would want to work for him if not exactly why Sammy would want to meet him in a motel but maybe that's why Terry is right about how boring life is in Stockville. Definitely one to put on your list: you can count on it.