I think it all depends on the time of year you go. If you go during the summer, the ship will have a great teen program. If you go during the off season when school is in session, the program will hardly be existant.
My wife and I just got off Carnival Miracle yesterday and there were only about 10 kids total onboard. The program was definitely scaled back to a level that I'm sure would not compare to spring break or summer vacation peak seasons.
I'm going on carnival valor and I'm going to be 16 does the cruise have a good teen group for my age??
Just got off the Valor on 10/8 and my kids are 16 and 18. They hung in the O2 club and hooked up with several teens on the ship. They had a great time and even went on an excursion as a group. The girl on there in charge of the teens was Lauren and she was 20 and very nice. That club is on the Lido deck right near the casino and other clubs. Im sure you will have a good time and meet other friends. I was concerned befor we went but we hardly ever saw our kids and they made many new friends to add to their my space list.
We have taken 2 cruises on carnival ships and will be on the Valor in 2 weeks. While there are fewer kids on a cruise this time of year our daughter has never had a problem finding other teens to hang with.
My son was on the Valor a few years back when he was your age. He met other teens and had a good time just hanging around, he's not much for organized activities, but there are plenty of those too, as well as teen dances, movies and excursions. Have a great cruise!