Just off Oasis last week. It's my understanding the drink packages are the same across all Oasis class ships.
I had the soda package and never even opened my cup! I just got soda from any bar we were at or restaurant we ate in from the server, both in MDR and the specialty restaurants. DH and my parents had the alcohol package and they all were able to get cocktails, beer, and wine in the MDR or any of the speciality restaurants. The only hiccup we had is that the package includes wine by the glass up to $13, and many of the wines by the glass on the menu in the MDR were more than that. They would have been charged the difference in price if they had ordered one, but they were able to find wines within the package instead.
Another tip - the soda package does not include bottled water, but DH was always able to order his drink and a bottle of water at the same time, and give me the water. Have fun!!