Anyone been to Big Day Out?

I'm coming to Australia for a month and half from the states to work the Australian Open. Big Day Out is the day after my last day of work so I'm looking to go with some coworkers, anyone able to let me know what it's like? $165 seems like a lot for only 1 day. American festivals usually go hand in hand with drugs and partying, is it different in Melbourne? Any advice or insights much appreciated. Cheers!