I never enjoyed this movie as much as I did when watching it alongside my 4-yr old twins.
I was iffy on what they'd think about it. I knew there was some questionable subject matter within, the kids were pretty mean, Jack had a few situations where he got pretty nasty towards others and the obvious of Jack getting shot out of the sky and Oogie Boogie shooting at Jack with his contraptions.
However, I was willing to risk it, sit with my girls and explain the situation. In the end, it was worth it. I think they appreciated that the kids there were being nasty. That Oogie Boogie was bad, and that Jack was just confused about what he really wanted.
I know there are some things they don't FULLY get, but as long as you're willing to sit, explain and stress that there are things inappropriate about the BAD things, there are SO many good things about the movie.
The music, the end morals of wanting to be different, better and of course, the love story.
Give it a try by yourself. You know your kids the best, and will know if this is right for them. But heck, if you haven't seen it... DO. It's great for adults, too!