We are doing Plus on a 14-day Christmas cruise to New Zealand this year. We are only interested in the drinks, and probably won't even use the wi-fi, special desserts or fitness classes. (One of the joys of cruising for us is unplugging and detoxing from our devices.). However, Plus is slightly cheaper than just the drink package. (Crazy!)
We are moderate drinkers and voracious coffee consumers, so we expect to break even or come out ahead. Also, we like not having to worry about how much we are spending on drinks and just have whatever we want, whenever we want. That alone makes Plus appealing for us.