I'm very happy with my experiences as an EMT. That said, you'll have a hard time doing anything with it until you're older. Most paying jobs won't accept you until you're 21, and only volunteer fire departments that are really hurting for people will maybe take you in.
If you're looking for clinical experience, start with some volunteering, like the Red Cross. If you decide you still want to pursue work as an EMT, do it when you're closer to 21, so you can practice what you've learned shortly after licensure/certification. Do it now, and you'll probably end up forgetting most of it before finding a job, and you'll be a liability.