Soft drinks are NOT free and unlimited on Princess. They do have a drink card - something over $20 - which is good for fountain drinks only ... no canned or bottled drinks. You can get coffee, tea and iced tea free. I've never bought the drink card but I think it amounts to a sticker placed on your sail card which you carry with you at all times because it's also your cabin key.
I cruise the Emerald Princess, Eastern Caribbean on April 16, 2012