Great Movie, but not for pre-schoolers
The beginning of a beautiful record of movie making by Pixar. They're often the best movies of the year, live or animated. Good date movie (for my wife and I, for example.)
And 6+ year olds are the right target. Pixar movies are not for 3, 4 or most 5 year olds. The scare factor is one obvious thing, but not just because it's scary. Being scared is a fact of life. Being scared by a big-screen, loud movie, crafted by professionals who can dial it up an order of magnitude past anything the kid is likely to ever possibly encounter in real life, is another thing. Just because your kid doesnÃ¢Â€Â™t melt before your eyes, but may even say they like it, doesnÃ¢Â€Â™t mean itÃ¢Â€Â™s ok. Basic child development hasnÃ¢Â€Â™t evolved as fast as film-making ability. WeÃ¢Â€Â™ve got plenty of time to ramp them up to hyper-media.
Another factor is how the characters, the friendly ones, treat each other. Constant insults, name-calling, bickering. Makes for a great film, but if that was what my household was like, IÃ¢Â€Â™d have some pretty obnoxious kids. 3-5 year olds are sponges, remember?