Last December we were on the Millennium in Southeast Asia and the first couple of nights there were a few more inebriated people than I had seen on previous Celebrity cruises, but after the second or third night a rarely saw anyone who had drank too much.
The second night I was returning from the casino and I had actually won some money. To celebrate I stopped at the Martini Bar and ordered a Martini. There were two couples at the bar and they were clearly over the "legal limit" but not obnoxious. I had a nice conversation with one of the women, drank my drink and headed back to the cabin. A few days later we had a sea day and she sat down next to my wife and I on the pool deck. I started talking to her, called her by name, but she had no idea where we had met. I told her it was at the Martini Bar. She then informed me that they had purchased the "All Inclusive" beverage package and it was a mistake. She said: "We drank too much the first two days and now we don't even want a drink. The hangover was too much."
I could never justify the all inclusive $50/day price. I can't drink enough to make it worthwhile and it would be a real waste of money on a port intensive cruise.
I've sailed on Carnival three times since they initiated the Cheers Program and haven't noticed any more inebriated people. Even on a four day cruise on Inspiration. Maybe they are just use to it.