I am in the same boat. (Ooohhh, that was terrible, sorry.)
I've never actually been on a cruise of any type. Although a tropical cruise sounds like something I would enjoy in theory, the thought of being stuck out at sea with a huge throng of other people just makes my introverted, social anxiety-filled heart cringe!
I'm quite introverted and anxiety-ridden myself, and I don't even like the ocean or being around water, but I thoroughly enjoy cruises. In fact I think it's become my favorite type of vacation. I enjoy the endless food, entertainment, and an interesting new port nearly every day. It's basically like being at an all-inclusive resort that changes location so that you get to explore new places each day. You show up to the ship and everything is taken care of, no having to worry about transfers or checking in to new places or exchanging currency, etc. You just enjoy your floating hotel.
I loved my experience on the Star Trek cruise, as you can see from the thread that 1001001 linked to. The decor, costumes, entertainment, etc. were all better than I expected. I also prefer Norwegian Cruise Line, which is the line that puts on the Star Trek cruises, so I already knew I would like the ship and service. Even for someone who does not drink, did not really socialize, and mostly stood off to the side at the parties, I had a great time. It's just a good feeling to be surrounded by such an inviting and accepting crowd that you share this thing with. The actors mingled with the rest of us more than I expected, and fans did not pounce on them. It was all very respectful. If I could afford it, I'd go every year.
The experience wasn't absolutely perfect; there were a couple of issues with the celebrity-led excursions, which were run by the company that puts on these theme cruises rather than by Norwegian. It worked out for us because we just happened to want to go on a specific excursion that was only being offered as celebrity-led anyway, so I don't feel like I "wasted" any money, but several people on our excursion were unhappy that they did not get to spend more time with the actor. To his credit, once he and his handler were made aware by an unhappy member of my group, he made an effort to move around to all of the different groups on the trip. It was really the company's fault for not planning better, and misrepresenting the exclusiveness of the experience. I enjoy excursions and would still recommend them, but I would skip the celebrity ones. There were enough other opportunities to run into them on the ship that I don't think it's worth the money.
It's definitely expensive. The first year they had one voyage that had a huge waiting list, so the second year they had two voyages that I think just barely sold out. Up to the week before they were selling rooms for very cheap. This time they are back to one voyage, so it will probably sell out before it gets to that. It looks like several categories are already fully booked. To be sure you get the room category you want and the best room selection, I suggest booking before the Las Vegas convention in August. Apparently they sell a lot of rooms that week.