I'd recommend people try cruising without any preconceived notions. People like or dislike it for their own reasons.
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That is good advice for most travel. My wise mother once said, you should keep an open mind when traveling. She was right.
And if you are traveling overseas, you have to remember that other countries don't do things or have the same comforts as we do. You have to be flexible and willing to adapt.
Carnival has received the worst PR for a spate of mishaps in recent years, but the truth is that every cruise line has had some misfortune at one time or another. These bad events just didn't make it to the media. However, cruising is safe — it's not the Titanic. In fact, as a result of the Titanic, various measures were put into place to assure passenger safety. And all ships are equipped with computers and what not to spot any trouble (eg. a hurricane) so it can be avoided.
I recommend for those who have never cruised before to take a short cruise first — say, a 3 day cruise from Florida to the Bahamas and back. That was my first cruise. It gave me an idea of what cruising was like and what to expect on any future cruises I might take. But if I found out I didn't like cruising, I was stuck on the ship for only 3 days instead of 7, 10 or more days