Yes, they limit you to a 28' wingspan, 20' length, and 10' height (including the detachable cart). Weight limit is 400 pounds, and we were at around 382 pounds with a 110 pound pilot. The span limit isn't ideal for a glider, but it's workable.
Most folks seem to neglect their Center of Gravity, and it ends up too far aft or forward, which can cause an otherwise flyable (in a very, very loose sense of the word) craft to nose dive or tail slide. We made sure that our CG was in the optimum range, though it appears that just a bit more aft would have gotten us a little more distance.
Most just fall, but Red Bull prefers them to fly because that's why people come to watch, and that's what gets them excited.