I've finally seen the movie Up, which appeared five years ago (and not to be confused with Up in the Air, which came out the same year). Reports had been that the opening sequence was brilliant and the rest merely OK.
That's about right. A mythic story should have a deep internal coherence to it; this one had a deep internal incoherence, though superficially it was explicable enough. Spoilers are necessary here.
First problem: The deep story in Up is of a man who learns to love more than himself (and the memory of his dead wife). This is expressed by his giving up his clinging to his house and saving the bird instead. The problem is that he doesn't evolve from the one position to the other; instead, he jumps back and forth, and his motivations for changing are given no weight, no heft. The fact that, even at the beginning, this grumpy "get off my lawn"-type curmudgeon is shown as tenderly devoted to his wife's memory already sends mixed signals, instead of being, as it should be, the hidden key to eventually cracking his shell (see Ebenezer Scrooge for a better job of conveying such a character, much as I hate to praise Dickens for anything).
This also shows in the way that the story is framed as Carl's quest to get to Paradise Falls, and when he finally gets there after a lifetime of effort, the achievement is just shrugged off, the story having been hijacked by something else.
Second problem: The protagonist's childhood hero turns out to be the villain; not just deluded but a cold-eyed murderer. This is vertiginously disconcerting, and is addressed only in one offhand line of dialogue. And what is the villain's evil plan? To bring an unknown animal to the light of scientific discovery. I'm sorry, but I cannot consider that a villainous motive, any more than I can that of the scientists in E.T. To embed that motive in villainous behavior, both towards the animal and towards our heroes, is even more vertiginously disconcerting.
Third problem, and this one it shares with almost every recent movie of its kind except Shrek: the climax of the plot becomes a theme park ride, full of exaggerated adventure underivable from the setup. For instance, Russell, clearly established as a Boy Scout who can't climb a rope (or build a tent: how'd he get all those other merit badges anyway?), now climbs a rope.
It's not that there's anything fundamentally wrong with the story being told, it's just told badly. As so often, especially for animated movies, millions for SFX and not one cent for a script. Well, this time a few cents, but not much more.