The parade is awesome, the fireworks are fantastic. The castle shows in the past are great as well. As other posters have mentioned, there is just this feeling in the air at
MNSSHP that is amazing. The rides are walk ons, the castmembers are even more joyful than usual, fellow guests are dressed up and in a bubbly mood, Main Street is lit up, the Ghost Host makes announcements throughout the night, the candy is being thrown at you.
For those that say they go to Disney to feel like a kid again, MNSSHP is a great example of this. The people who attend this event are typically uber Disney enthusiasts already, and the mood is palpable.
I want to add that I would not say the same of
MVMCP. It's like MNSSHP is our secret, Disney fandom meeting. If you love WDW, go!