"9" is an animated movie aimed at an adult audience. That's not to say it is filled with sex, nudity, and bad language - it has none of that stuff. Instead, it is an animated movie for adult minds - with stuff you don't see in a family animated movie. It is often downbeat in nature, it unfolds at a slower pace, there are deaths (at least I think they can be called deaths), and the colors are dark instead of being bright. So most (not all, but most) kids will probably be turned off by it. However, more mature children and their parents will enjoy it. The story slowly unfolds at a pace that will keep you curious as to what the explanations for things will turn out to be, each of the characters are unique instead of being all alike a la Ninja Turtles, and the animation is very good. There are a few plot holes that come up, mostly when the movie is over and you think about it, but the movie is still an enjoyable and unique experience.
