We have been on 15 cruises + total in the last 12 years, about 10 of''em was on Carnival. Until about 2008 Carnival was OK, then it started to slide down cutting service, food quality and variety.
One of the last Carnival cruises from Tampa to Cozumel our state room was freezing cold and they were not able or willing to fix the problem, neither they offered any compensation for that. I also noticed that Carnival ships were cheaply made in Italy, Carnival obviously did not make much effort to keep them safe and sound as the latest "incidents" prove.
Other cruise companies like Royal Caribean have their ships built in Finland and if you,ve been on both you'll see the difference in construction quality.
I do not plan to sail on any Carnival ship until they really get their act together if they ever will.
As for CCL stock I never owned it, but I plan to buy some serious puts if the market auction warrants it.