I have two experiences of Pleasure Island: being 21 and being under 21. Here they are (just so you know, you have to be 18 to enter Pleasure Island without a guardian):
Under 21
When I was 20 (I was turning 21 in a month--how annoying is that), I was slightly frustrated by the fact that my friend was 21 and I was not, so that kinda dampered the effect. Those of you with fakes, these people are psychotic about checking your ID, so don't even try it. They ask you to smile, they ask why your hair is a slight shade lighter (sorry, I needed highlights again)--it's a bit overdone. We arrived around 10pm, and the clubs were pretty dead. However, they do pick up around 11:30pm. My friend and I only visited Motion, because it's an 18-and-over club, and at every other club you either have to be 21, or it was for the older (meaning 30+ crowd). Now, I'm from a small town in Ohio, and all there is in my city are smoky pubs, so this was a nice change to me--NO SMOKE! I loved it! You do not reek when you leave here! The music was great Top 40, and no one looked overly slutty or thuggish. I couldn't drink, so I just danced the night away and had a great time! I would suggest arriving early, though, because the lines do get extremely long after 11:30pm.
Being 21
At 21, you can buy separate tickets for each club instead of paying a full admission. We still decided to pay full admission. Just so you know, the drink prices are very , so bring plenty of cash! The music this year at Motion was horrible. It was all mid-90s music! I was having flashbacks of junior high dances! We decided to go to Mannequins (which is a 21-and-over club) to see what it was like. (Disclaimer: I am by no means a homophobic person--I have many gay friends and work in men's retail. I am just making an observation.) The club was mostly gay. I don't believe it is listed as a gay club, but I had heard previously that many gay people did hang out there. I had no problem with this because gay clubs usually do have better music and dancing. Just throwing out a warning for girls looking to hook up with guys at this bar--it's probably not gonna happen. The floor rotates, which is awesome (bad idea if you are drunk, though), and the music is incredible--I had a good time, but I could only dance with my friend because no guy wanted to dance with me. It's fine, though--I still had a lot of fun.
So there are my two experiences. I did have very positive experiences, and I encourage you all to visit PI; it's a great time for spring breakers. The Disney Shuttles still schedule pick up till around 1 or 2am, so it's very safe and convenient!