I think the short answer is, "It depends."
Personally, I learned a lot in high school, but I learned more faster in college, and that had more to do with the college environment than it did with me being more mature. I thought about attempting to graduate early, but it could come with some big drawbacks.
The first question is when do you turn 18, and do you plan on living at home while going to school?
Trying to move out before you are 18, even to a school dorm, creates complications that simply vanish when you are 18. (For instance, you generally can't enter into any legal contracts at all until you are 18).
So if your plan is to live at home (at least initially) then graduating early might make sense, but if you want or need to move out to go to college, then I would wait.
Next is how is your savings. Do you and or your parents need that extra year to save before you start college? I did and then I worked thoughout all of my college to keep my debt low.
And then, to echo so many other posters, how is your social situation? I personally consider this the lowest point on the list, but you really don't get many chances at senior prom or some of the other unique social events.