you should definitely go. Unless you are an extrovert who enjoys small talk and befriending new people at every possible occasion, I recommend going with friends.
I have just returned from an 11-day Caribbean cruise (Fort Lauderdale - St. John's, Antigua - Pointe-a-Pitre, Guadeloupe, Bridgetown, Barbados - Fort-de-France, Martinique - Castries, St. Lucia - Basseterre, St. Kitts - Half Moon Cay, Bahamas - Fort Lauderdale), that I'm trying to summarize for my undecided readers. It was a new and definitely positive experience, without the slightest motion sickness I was a bit concerned about before leaving.
The best part for me was enjoying the view, especially approaching an island, observing the land getting closer and the behemoth ship maneuvered in reverse with millimetric precision to the pier and anchored.
The Caribbean beaches with their turquoise waters and white sand pictured in brochures don't tell the full story (excluding the Half Moon Cay private island). The part they usually miss is the poor conditions in which the local population lives. Add the hot and humid climate (with occasional hurricanes), perceived lack of personal security in a tumult of taxi drivers/guides and merchants invading your private space (a western notion) and the island visits can be quite unpleasant. BTW, taxi prices drop dramatically, the further you walk from the port.
Some practical pre-cruise advice: make sure to arrive to the starting port a couple of days before embarkation to avoid any unforeseen flight cancellations or delays. These couple of days came in handy for us as our luggage was not on the first flight, due to a sudden airport luggage strike on the first leg. For any flight, not just pre-cruise, pack one day's essentials in your hand luggage - we didn't do this and needed to shop for underwear and toiletries right after arrival. Not that there is anything wrong with underwear shopping, but there might be more interesting sites to visit than a shopping mall.
And while we are at packing, I want to refute the common belief of needing lots of elegant attires on board. The cruising industry is undergoing a major change from old world classic elegance, decor and service, to a more modern concept that appeals to younger generations it is [successfully] attracting. The industry is expanding and will continue to do so according to various analysts. So, if you are not an evening gown/black tie person, just bring whatever clothes you feel comfortable wearing, and a few elegant outfits for formal dinners (that you can BTW avoid completely, although I recommend against).
A major aspect of any cruise experience is the food. It is tasty, diverse, tempting and always around you. You will definitely gain weight, even if you have the strongest will power to avoid temptations. However, you can work out in the well-equipped gym with a fabulous view, unless you prefer the treadmill monitors instead (don't). They offer various classes as well. In addition to the many food options included in the cruise price, you can also dine in high-class restaurants, or go to coffee shops and bars.
Entertainment on board was one of my most pleasant surprises. All the performing artists were really good, be it bar pianists, classical ensembles, singers, dancers or comedians. Turns out that entertainment jobs on cruise ships are very sought-after. The on-board productions were rich and well-choreographed, with advanced use of video technology blending in the theme.
Cruises are well-oiled machines for extracting as much money as possible from guests, a captive crowd for expensive products offered on-board, such as jewelry, art (not to my liking), alcohol, perfumes and expensive clothing. Also some on-board lectures are sales-oriented. You can gamble in the casino, get body treatments or go on shore excursions. Alternatively, you can spend time around the pool and Jacuzzis, where you will probably consume cocktail, beer or coffee.
We took two group excursions: one to rum distilleries in Barbados (guess who wanted this one) and a dolphin encounter activity in St. Kitts (the preference of yours truly). Local shopping is either in tourist-only areas or in local markets and shops, where the offering is usually [made-in-China] souvenirs, foodstuff, clothing and costume jewelry. Makes you think that the beads given to the natives by the colonialists in exchange for gold are now sold back to them for dollars and euros.