We were there NYE 4 years ago, and while the park stayed open until 2 or 3 in the morning, it was too packed to really do anything. We entered the park late afternoon/early evening, and it literally took us 1 hour to make our way back to New Orleans Square. It was wall to wall people, and they were barely moving. We decided to take a break and try to get something to eat, and the line for the restaurant (can't remember which one, but it was a counter service) took another hour. We couldn't believe it. If you have the time, I'd definitely wait for the 2d or 3d before attempting it.