Why are they painful? Because every time you "conveniently" take them off to "eat or brush your teeth" your teeth are loose and moving them around hurts like hell when brushing or eating. Snapping the braces back on and they'll hurt like hell again for about an hour until the braces stabilize them and they start settling again.
It was a huge waste of money, and now I'm saving up to get traditional braces. My teeth aren't even all that crooked, traditional braces can straighten mine out in less than a year.