My family went back when I was a teenager. It was one of my favorite vacations, and I think I'd appreciate it even more as an adult. The beaches were nice, and I got to stand at the southern most point in the U.S. and look across the ocean towards Cuba. There were street vendors and performers, which created an overall laid back vibe. Lots of water activities to keep anyone entertained. My sister and I went parasailing, and we got to go out on a snorkeling excursion.
I think what set it apart from other beaches I've experienced was the atmosphere. I'd describe it as slightly more mature content, meaning there were more adults, alcoholic beverages being served, a little more of a party vibe, but in a way that didn't seem threatening or too wild. Just a lot of people relaxing, enjoying themselves in the sun and having fun.
I also remember how nice everyone was to us. From the people who worked on the boats that took us snorkeling and parasailing, to the waiters at the resturants, I remember tons of hospitality.
One day, it'd be fun to goo back and I'd recommend it to anyone looking for a fun beach vacation.