I had braces from Novemeber of my junior year in HS to 3 days before my graduation and hated every second of it.
Firstly, they make it a lot harder to eat and keep your teeth clean. You have to brush your teeth after eating anything, because 20% of what you put in your mouth stays in the braces. Get used to not smiling for a few hours after meals, or carrying a toothbrush with you everywhere you go.
Second, they had no long-term appearence benefit for me. My teeth were only crooked in the back, so my smile was fine to begin with and no different after the 18 months wearing them.
Third, they detract from your appearence significantly. Of course they don't make it impossible to DJ, but girls notice them and don't like them. The younger you are, the less negative effects they have, but I was one of maybe 5 kids in my senior class of 400 that had them. I actually had experiences where I would make eye contact with a girl, she would smile, and then when I smiled back and revealed the braces she started laughing. It really starts to get annoying after awhile.
Fourth, they are very expensive. Thankfully my parents paid for mine, but if you have to pay for them yourself that just adds insult to injury. If I was living my life again and someone had offered me $4000 (the cost) to wear braces for the last 2 years of HS, I wouldn't do it. Seriously.
I would recommend getting braces only if your teeth are so screwed up that you won't mind going through 2 years of **** to get them fixed. In any other situation, I just don't think its worth it.