Easily one of the weakest installments by Pixar.
The art and animation in this piece is beautiful, but the plot is paint-by-numbers, with themes and exposition ripped off from other animated features, characters borrowed from other places and a plot-arc that is predictable half-way through the opening reel.
There's nothing particularly harmful or offensive in this piece and it is rendered beautifully to be sure, but it also never challenges you, it never surprises you and its humor is mostly focused on prat-falls, chase scenes and an abusive bully who hits people.
The main villain in particular has no motivation, depth or growth, as a result you can neither like him or dislike him. He seems more like a plot device than an actual character.
Many other characters seems borrowed from other Pixar features.
The Mom and Dad characters are about as cookie-cutter, overly protective middle-class suburban parents as you can get. Making them also thin, dull and entirely predictable. The father is absent and distant, the mother is overly-protecting and frightened. You've seen this dynamic a million times, so you become bored with their depiction immediately.
I think this is a fine kid's film, it was obviously a lot of work and my praise to the artists and actors who made the film. The writing however is drab, formulaic to the point where anyone over the age of 10 is going to be a little bored, because the plot never challenges you and it doesn't cross deep emotional lines.
It's one of the first Pixar movies I've ever seen where I neither laughed out loud or shed a tear.
I think this film can be described best by one simple word: "Meh".