I want to live in San Fransokyo.
Big Hero 6 takes place in a slightly futuristic combination of San Francisco and Tokyo, the whole city (but particularly the Golden Gate Bridge) having a slight oriental flavour that when mixed with the signatures of San Francisco create a visually stunning and unique location for this film. The technology of this world is slightly in advance of our own, and there is an abundance of it - Hiro Hamada, our main character, makes money by betting on robot fights, and both he and his brother have a vast wealth of technology available to them to experiment with. This creates a fantastic little world which you are drawn into immediately, a perfect example of world building in cinema and a great place in which to set this kind of story.
The film follows Hiro as he attempts to find out who is behind the theft of his Microbots (an invention of his that earned him a place in a prestigious technology school) with the help of Baymax, a healthcare robot that his brother designed, and his friends/lab partners - Fred, Wasabi, GoGo and Honey Lemon, each of whom are experts in their field, whether that be lasers, magnets, chemicals or even, in the case of school mascot Fred, superheroes.
As indicated by the title, Big Hero 6 places a heavy emphasis on the way Hiro, Baymax, and Hiro's friends interact and work together for a lot of it's run time, and it is in these areas that Big Hero 6 is strongest, particularly in it's first two acts. Hiro himself is a pretty great character, but I was more impressed with how great each of friends are - they are all fully realised characters with believable personality traits from the second that they appear on screen, and their love for Hiro as the film progresses is incredibly endearing.
But it is Baymax that steals the show here. This gentle giant is responsible for all of the funniest and most heart-warming moments in the film, as well as a particularly harrowing sequence when his programming is changed that has a genuine emotional impact on the audience. Baymax is by far and away the best aspect of an already pretty wonderful film, and a great example of how to properly personify an object that is essentially inanimate.
It's hard to fault any aspect of Big Hero 6 if I'm being honest. It's consistently funny, with great characters, a strong story and a compelling emotional core, everything you would want from an animated feature like this. I'd go so far as to say that Big Hero 6 is as strong as any animated feature out there, and I'm including the mighty Pixar films in with that - Big Hero 6 really did an awful lot right, and there is no one that I wouldn't strongly recommend to.
In short? Go see Big Hero 6. I doubt you'll regret it.