The movie is about an eleven year old girl named Riley, who moves from Minnesota (leaving her friends and the the lake where she learned to ice skate) to San Francisco (where they've ruined pizza by topping it with her least favorite food: broccoli). But it's also about Joy, Sadness, Anger, Disgust, and Fear who live in Riley's brain. Joy and Sadness accidentally get sucked out of the Command Center and transported (via tube) to Long Term Memory, leaving Anger, Disgust, and Fear at the controls, and have to find their way back.
(If you're planning to see it and want to be surprised, stop reading now.)
There were moments I whispered to my preschooler, "We don't say that," or "She shouldn't have done that. That's not nice." For example, there were a couple of stupids, a shut up, an idiot, and a moron. There was a moment where Riley was sarcastic and then yelled at her parents, but I was happy to see her father tell her to go to her room. ("See, Riley got a time out," I whispered.)
There were also things that went over my daughter's head, like a gag about a Fabio-esque Brazilian pilot, an imaginary "boyfriend," and the line, "What's poo-ber-tee?" Did the movie need them? I don't think so. But they went by very quickly.
The movie also had moments that made me cry. Some of Riley's happy memories are put into the dump, and they turn to dust and blow away. And later, when my daughter asked in a worried tone, "Mommy, why is he disappearing?" of Riley's imaginary friend (an elephant/cat/dolphin made of cotton candy), I didn't answer because I didn't want to upset her more.
I thought it was nice how Sadness was able to make Riley's imaginary friend feel better (when Joy couldn't) by empathizing. And I related to Joy; in many ways, she's like a mother. She loves replaying Riley's happy childhood memories, and Riley's happiness is Joy's priority.
And, yes, that made me cry too.