I'm a senior in high school right now, but my junior and senior year I have taken all my classes at the community college through the state's Post Secondary Enrollment Option (PSEO) program. When I graduate from highschool this spring I'll have my (free) 2-year degree. When I get to college next fall I'll be a 17 year old (I skipped 2nd grade so I'm younger than all of my current classmates) Junior entering a program that is probably going to be full of 20 and 21 year olds. It will be weird at first but I'm not too worried. My parents have always said they're only going to pay for 1 year of tuition at a state school, the rest of my education bill is my responsibility. If I would've just taken regular HS classes I would be looking at taking out a huge student loan to cover everything, this way, worst-case scenario, I will only have to take out a $15,000 loan.
I'm not a huge fan of highschool, if you don't particularly like it then I would definately say ahead and try to get done early.