I'll go a little more in depth now that I have some more time.
The drink package is a per person package and only one drink can be ordered at a time. It is good for any bar venue on the ship including the pool area. There is no self-serv on the ship. All drinks are handled by the bar staff.
There are different packages that allow you to have different drinks. The top package allows you to order just about any drink or brand on the ship. Lower grade packages are limited to beer, well drinks or blended drinks.
Depending on how much you drink per cruise it can be a good deal.
The top shelf package is around $500 per cruise.