We just got back from WDW, with 3 kids in tow, 14, 11, and 3yo. I'd say most of the kids were dressed up in costume, if they weren't most had some kind of Disney Halloween t-shirt or sweat shirt on. The night we attended my wife and I guess about 80% of adults came in costume, that was some of the most entertaining people watching I have ever done!! Plenty of pirates and pirate families, we even saw a family of 6 all dressed as the Incredables!
Our 3yo had a great time and wasn't scared at all. Usually I'm not much of a parade person but this one really caught my eye and ears, the music was catchy and flowed well with the parade. CM's actually hand out a little bit of candy at the end of the parade, but for $35 a head we weren't there to get Wonka candy that you can buy at the stores. Make sure if you do plan to collect candy you get a special orange treat bag, they won't just hand candy out to you unless you have one, and you have to get them at the park entrance! Don't forget that! We liked this party better than the Christmas one!! We'll come back to this one in a heartbeat! As noted some rides are closed. Plenty of decorations on Main Street, make sure to look up on the buildings there are pumkins in the windows, free face painting but get in lline fast, CM's take your picture but we didn't wait for that, unlike when we attended the Christmas party, it just seemed like a long wait for a picture you had to pay for. Lines went fast for the candy later in the evening, rides lines were about right after the first parade. We didn't do everything that was offered but did enjoy the amazing fireworks. My wife missed the headless horseman, but I got to see him right before the second parade while I was watching our 3yo, who was sound a sleep. Next time we adults would dress up and join the party, it was a hoot for the kids!! My 11yo son came as a slice of pizza and you should have heard the CM's and other guests make comments. Several CM's stopped him just to tell him how much they liked his costume, it made his entire trip!
Was it worth the extra $35 bucks? HECK YES!! Oh, and go early, they let us in at 5-ish but I'm sure you could have gotten in a little sooner.

The entire night was hauntingly magicial!