Mei (voiced by Rosalie Chiang) is a 13 year old girl growing up in Toronto with traditional Chinese parents. She has three good friends at school (each with a huge and specific personality to make us think we "know" them even though they don't get that much screen time) and a life that involves a lot of schoolwork as well as helping take care of the family temple. But between her over-protective mother repeatedly humiliating her in public and/or at school and her and her friends desperately wanting to go to 4*Town's upcoming concert at the Sky Dome, she's got a lot to deal with. And then, in a moment of strong emotions ... she turns into a big red panda.
In the history of film I don't think there's ever been a more TORONTO film than this one - certainly not from Disney! So that's good - from my point of view. The CN Tower in multiple shots, city trolleys, and the big climax at the Sky Dome. And the fact that her school (and friends) are significantly racially diverse - that's just how this city is. So Toronto.
But ... I didn't like Mei. She's spectacularly annoying for most of the film. You kind of get why when you meet her mother, who's even more annoying. But "getting it" doesn't make them more appealing. When you toss in Mei and her friends' favourite music being the fake boy-band 4*Town (music by Billie Eilish and her brother Finneas O'Connell, which will probably appeal to many but not me), I found it a real struggle to stick with the movie. There are a lot of good moments, and the ending - despite being thoroughly over-the-top - does mostly redeem everything that preceded it. But not my favourite Disney/Pixar movie.
Despite that ... I gotta give Disney/Pixar some credit for taking this one on: most of us have an idea of "typical Disney fare" and this, this is not it. And that's a good thing. Also, reading the "Design" section of the Wikipedia page about the movie gave me some idea of how much thought Domee Shi put into her movie. You may think that it must be that all directors do that, but it's really not.