I have not sailed on a Carnival ship in six years. But every time I sail Cunard and Princess (4 or 5 times per year) I get a substantial discount. Discount applies for as little as 100 shares. At today's prices it is tough to resist adding more.
Sentiment: Strong Buy
I have cruised Princess too. But I have never gotten any discounts for being a shareholder in CCL.
You have to ASK. You get a cabin credit, depending on the cruise length.