It is a very crowded event, I used to go yearly with a church youth group, it is a fun event. Ride lines are very very very long and the event is full of teenagers, not all who behave properly, but the majority are well behaved.
In the long ride lines there is a lot of cheering and chanting that is actually a lot of fun! But if you want to avoid those long ride lines and experience rides during this event, for $15.99, you can get a express pass for the event (4 p.m.- 1 a.m.) This will save you a lot of time if you plan on riding rides.