I don't have a review formed in my head yet; the experience is still settling. Up is a much more mature, adult film than I was expecting based on the fantastical premise of a house carried away by balloons. In Ratatouille, Brad Bird sold me on the idea that a rat could control a human by pulling hair, but this film contains Pixar's greatest leaps of creative imagination yet.
And I'm not just talking about the house. (Remember, this is the spoiler thread.)
The bad guy has isolated himself from the world and is surrounded by his well-trained dogs. How well-trained? Well, there's one who can prepare delicious gourmet meals and three who pilot aircraft. Their steering wheels are bone shaped (and squeak when the pilot bites down.)
That all can go down fine in a kids film, something with a tone closer to Cars. But Pete Doctor sets high emotional stakes in the beginning, with a brilliant sequence that sets the film on very realistic ground. The emotions that underpin the adventure and carry this movie through, are often sometimes occasionally undermined the silly stuff.
I think what ultimately keeps the film on par with Pixar's other masterpieces - aside from the expected big laughs, eye-popping cinematography, (I'm saying it.), and overall technical mastery - is the intriguing counterpoint of the two old men. Our hero, Carl Fredricksen and the bad guy, Charles Muntz, are both people who go a little mad in pursuit of a dream that will take their entire lives and leave them emotionally empty.
Maybe it's because Carl's emotional stakes are so beautifully defined, but Russell the wilderness explorer doesn't fare nearly as well. His emotional story is underdeveloped to the point where I question if it's even necessary. Especially since Doctor has to stop the action to shoe in Russell telling us what's missing from his life.
There's more rattling around my head, but I'm going to wait for others to chime in.