I'm still in uni (still have 3 years to go!) but I'm loving it so far
However, it's very different to what I know about the usual American college experience cos almost everyone lives with their parents throughout uni years, like me. As for friends, I am in class with some of my friends from school (whom I've known since I was 3!) so in that sense it's not that huge a change either. I'm still seeing almost the same people I did when I was at school, except for the few who are studying elsewhere.
I have to say, if I had to choose between school and uni it'd be pretty tied, my school was great and everyone got on so well, I had loads of fun every day. The thing that makes uni so special to me is not the day-to-day fun I had at school, but the general freedom that you have to go here and there, party, etc (which I guess is more an age thing than a uni thing), and the fact that you can relax for 3 months then study like your life depended on it (which, heh it does) for just 3 or 4 weeks each term. With school it was more about constant work, but a lot less work than uni.