I saw this the past weekend. It's probably the best movie from 2009 I've seen so far. It also continues the Pixar streak: they haven't made a bad movie yet. This is an amazing achievement, and I keep thinking a clunker is coming, but somehow it doesn't. A Bug's Life was probably the weakest Pixar, and that's really saying something. Especially given the standard being set by other children's cartoons out there.
I was a bit skeptical of the premise for this film: man goes on a trip to South America by turning his house into an airship. Boyscout kid tags along. Sounds a bit wierd, right? But instead of being some crazy technicolor adventure, the movie turned out to be about aging, death, divorce, and finding joy in one's life, however one can. It was pretty heavy for a children's movie, which was evidenced by the confused questions some kids were whispering to their parents at the showing I attended. But despite that, all the kids I saw after the movie seemed happy and excited by the experience. I left the theater feeling the same way.