On the outset, Up doesn't look like your typical Pixar movie-- its lead character is a 78-year old grumpy man, and it shies away from the non-human protagonists in recent film releases (cars in Cars, rats in Ratatouille, and robots in WALL-E). But after watching the film, Up is a worthy film in the stellar Pixar catalogue.
You can appreciate Up on face value. It features a story about adventure and has a good mix of lovable (not to mention funny) characters. The kid in everyone will love Up on those merits. But look deeper and the film shares a lot of lessons, such as second chances, the price of success, and letting go. And the good thing about Up is that it executes in a very whimsical way.
I watched the film in Disney Digital 3D and I was quite disappointed with how the film, ironically, looks rather plain compared to Ice Age 3 and the previews of the 3D movies before the main screening. Another thing I'm nitpicking on is the quick wind-up of the story, considering the set-up was so superb. (Geez, the back story of Carl Fredricksen, the lead character, is already a movie by itself).
My nitpicks notwithstanding, Up is a must watch. It took me three days to get good seats for the movie and it was totally worth it-- you'll laugh and cry, but your spirits will be lifted by this film after.