Well it's pretty much the same as last year, just a little more drama, more freedom, and more homework. Also this is probably one of those years where you find your real friends and things like that.
There is definantly more freedom, more choices in things like classes, it's a little harder to keep up with work if you aren't organized, and like tamakitty07 said, most likely more drama.
It's was an overall great experience for me. Just make sure you keep up with your school work and don't get into gossip chains- that alone ruins so many friendships. x.X
