I agree with others that Up is a movie which contains something for everyone. This seems to be the case with most of pixar's movies. Much of the plotline, animation and dialogue is geared towards the young and young at heart. However, all these movies are loaded with one-liners and other references, and montages (such as the man and his wife in Up) which only more mature viewers would grasp. I think it's very wise to make movies in this fashion, not only does it provide entertainment which the whole family can gather around, but it also weaves a certain timelessness into the movie. The preteen that sees up now, can watch it in ten years and have a completely different movie experience.