Hmmm, magical. That's the best way to describe it. Magic Kingdom is open until midnight for guests with tickets. The party officially starts at 7:00 pm, but you can start coming into the park around 4pm. At 6pm, the park is closed to prepare for the party, and guests are sent to one of the lands to wait. Once 7pm comes around, the party is in full swing!
I highly recommend getting a special park map from the entrance of the park when you enter. It points out all of the special events going on during the party (such as a Holiday Hop dancing area with characters for the young and old alike), and things like free photos with Santa, and where the free cookie and hot cocoa locations are.
Almost all of the rides are still open during the party, and we never had a wait for anything the entire night.
After the parade, there was a special "Wishes" performance, which is Disney's 360 degree fireworks show. Bring tissues, because it will bring tears to your eyes-it is simply beautiful.
All in all, we are so glad we went to the party, and I am sure we will return again.