This is one of the first events we experienced at the WDW parks. Typically the weekend before and the week of, WDW closes a bit early and stays open a bit longer for the Mickey Not So Scary Halloween Party at the Magic Kingdom. This is a must if you are in the area around that holiday. Most patrons dress up and be sure to bring your trick-or-treat bag as you will surely get great treats from the characters.
There are lots of people who attend this, however many guest do not ride the rides (there is so much to do). This is awesome if you have a ride that you adore, you can ride multiple times without a line! Yes no lines! Where are the lines? There are lines everywhere else. Lines for shops, food, character meet and greets (where the do hand out candy), free pictures, etc.
Best of all is the awesome parade featuring a real headless horseman. It's an all around good time and worth the extra $30 per ticket for the event.
Tip: Buy the LE event pin