There is a great deal of new attractions like Everest rollercoaster, finding nemo stage show, Lights Motors Action car stunt show. I would suggest taking a Disney travel book out from the library. Also, be prepared for a very crowded weekend at the parks.
everest is awesome....I wasn't really expecting much when I first rode it, looking like Thunder Mountain on steroids....but after I got off I was very pleasently surprised. What a great ride. Also you need to check out Soarin in Epcot, this is a BIG must do.
If you have time hit your local bookstore and pick up birnbaums disney book...lots of helpful advice and you can kinda map out your trip what rides you want to hit and what ones you want to miss.