Special Parade
Special fireworks
The atmosphere in the park is something I cannot even attempt to describe. Sorry it is no help but if you do go, you will know what I mean. The lighting, the music - everything about it
Rare characters are out for meet and greets, character dance parties, the Villains Mix n Mingle stage show
Trick or Treat
Forget about 'access to rides' Yes, the lines are going to be shorter than on an average day but in spite of capped attendance, the parties are not a ticket to an empty park and the rides are fun in costume (especially if you have Photopass+ or want to buy a ride photo) but don't let that be a deciding factor.
Is it worth it? We don't like Halloween. We never do anything about celebrating it. We went to one party in 2010 and then every fall after that we went. Last trip we did we went to 3 parties (yes, same trip) It was worth it for us and I'd do it again without hesitation
I will add that we had more days there than park tickets so we used a party ticket for our last night after out tickets had run out and also didn't do a park on one of our other party days, entering at 5 pm on the party ticket so effectively we got an additional 2 park days which helped offset the cost (psychologically anyway)