Here's what my 23 year old son had to say about this past New Year's Eve.
"If you want my take on the Disney New Years atmosphere at MGM: There was a stage set up in front of the BAH and a DJ/MC guy was up on stage. They were playing modern music and people were dancing and all that. Strobe lights, etc. In fact, Chandra and I wanted to stay to enjoy the festivities but it was 6:00 and that meant being there for four hours. So, if you want to enjoy New Years Eve parties, show up early. I bet MGM is the best place to be since Epcot and Magic Kingdom are highlighted on ABC with Dick Clarks Rockin New Years Eve and are probably more crowded. That and MGM just lends more of a party atmosphere with all the neon lights and the BAH looks more modern and party-like than Spaceship Earth and Cinderellas Castle, which sells the feeling more for me."
Also, the kids and my mother-in-law had a great time since they were given New Year's top hats and noise makers and beads. This was around 5:00 and they arrived back at All Star Music dressed in fine gear. But at midnight, we were able to go outside of our building at Music and see the special Illuminations fireworks. Totally awesome and the same ones we saw one year at Fourth of July. My husband says it appears that Disney World takes every single firework in the state of Florida and explodes them.
Either way, it's going to be awesome for you.