[JossP80]

I've done a few through the Bahamas, and one in the Baltic... Enjoyed each and will probably start doing one every other year or so.

Everyone pretty much covered the main points. Different lines cater to different crowds. Depending on the ship, time of year, etc you can minimizing rough seas. Stay hydrated! Dehydration is a major cause of sea sickness (and even worse if you're a drinker)...

The food is usually very good (but for long-duration cruises you'll find the same dishes), entertainment varies in quality depending on what you're into. My gf ran 8-10 miles every morning and out into the towns on mornings we were at port. It's an easy way to package multi-country/city travel.