Uh Oh. Just How Scary Is The Movie, Anyway?

[Cindy C.]

I heard a few people who have seen the movie mention that it is 
scary, and that it should have received a PG-13.  Just how scary is 
it, how long do these parts last, and how did the children (say, 4-5 
years old) in the theatre react?  Were parents sprinting up the 
aisles to take their traumatized offspring outside, were the kids 
crying, or what?

I'm seeing the film with my three kids on opening morning in the 
U.S., but I can leave the youngest with relatives if the film will 
really be more than he can handle.

Thanks.

Cindy