Alisa and I caught Pixar's Up three nights ago. What a great film! Possibly Pixar's best film to date, and that's saying a lot. It opened the Cannes Film Festival this year and received an 8-minute standing ovation, Roger Ebert gave it four stars, etc.
Up is one of those films where the marketing for the film didn't really match the actual movie (another such film is the excellent Zero Effect). The trailers made Up look like a campy adventure movie, but the truth is that the trailers showed only the campiest parts of the film and little else. While there certainly is adventure and campiness, Up is also sentimental, sad, sweet, and even romantic.
I can't puzzle out how kids would react to Up. Perhaps the deeper aspects of the film go over their heads, and for them it really is just a campy adventure film.