Well done. Works as an action movie, but also a mystery puzzle. It will have you thinking about "the answer" for days. If you like a good head scratcher then this is for you.
Not going to win an academy award by any stretch, plot completely and utterly predicable, but the characters were likable enough and the dialogue and slapstick witty enough for a laugh or two. Also, something you can take your tweens to see without too much embarrassment either way.
Up is a great movie. The 3-D took a bit of getting used to (I am slightly miopic) but once the story and visuals took over I really enjoyed it. There may not be enough silliness for really young kids (though the dogs are hilarious--and you may get requests for Doug dolls this christmas). The themes of aging, death, loss, life choices are pretty deep, but well done even for young ones.