DS and his friend went with us the first time when he was about 12 or 13 during the earlier part of the evening. They both enjoyed the AC and CC. The material was along the line of PG13 which was fine.
When DS was 16, DH brought him and the nanny (age 18 - who was on holiday with us as we also had a 14 mos old) out for an evening at PI - They had a blast dancing in some of the clubs, did the CC, and then more dancing in the street until midnight. While there were guests there who were drinking and smoking, this didn't really have much impact on them and the parts they fondly remember is what a good time they had dancing during the evening.
I agree with Marriedmarylander, that PI isn't a trashy place, and while "grown up" things may be happening there; for the most part I think of PI as a safe place - it's not as if I set the teens loose at PI, they were out with us and from what I've seen it's mostly just tourists out looking to have some fun. By the time my kids were 14 or so, they were well aware that "grown ups" sometimes drink, smoke, and do stupid things. That's just part of life. Some people prefer to shelter their kids from this, and those parents would probably be uncomfortable bringing their kids to PI, even during the earlier part of the evenings.