Pixar has proven itself capable of great pathos before--Jessie's story in Toy Story 2, the prologue to Up, the climax of Toy Story 3--but it has outdone itself with Inside Out, dealing quite literally in emotions while also playing with (and if you know the premise, this makes perfect sense) the emotions of those emotions and the emotions of the audience.
Consider the following a minor SPOILER, because it offers up more than the trailers do. Inside Out is about an 11-year-old girl named Riley (Kaitlyn Dias) whose life is falling apart after her parents move the family from Minnesota to San Francisco. But really, the film is about so much more, and the personified Joy (Amy Poehller) and Sadness (Phyllis Smith) and the imaginary friend Bing Bong (Richard Kind) are the real show here. Joy and Sadness get accidentally removed from the headquarters in Riley's mind and (major SPOILERS ahead) Riley's internal world starts literally falling apart just as her external world figuratively does. Most of the film takes place over the course of a single night and day in which Joy and Sadness, with the help of Bing Bong, try to get back to headquarters so Riley will not be an emotionless preteen.
The plot is actually fairly simple, but insightful dissection of this little girl's emotional state works quite well as a representation of all of our emotional states. There is truth to this film--just as there has been in many a Pixar film. And, not to be too obvious about it, there is great joy and great sadness as well. Anger (Lewis Black), Fear (Bill Hader) and Disgust (Mindy Kaling) have their moments, as do the emotions of Riley's parents (Diane Lane and Kyle MacLachlan) and of several other characters at the end of the film (living in a house with three cats, I must say the representation of a cat's emotional life was dead on).
The design of the headquarters and the rest of Riley's mind is not, as one might expect--and as its simplistic version early on might seem), arbitrary, but quite logical, and the reason for the simplicity is explained--SPOILERS, simple version, Riley was a child so her interests were narrow, more complicated version, Joy was overbearing and overprotective.
Ultimately, the idea that we need sadness to get by is not a novel concept but it is a powerful one.
Inside Out is Pixar on top of its game once again.