They had a piece on the local news awhile back about this. It literally is like the robot arms they use in the car manufacturing industry. It has multiple joints which allow it to twist and turn. At the end of the arm, is a compartment that seats two people. It goes up and down, twists side ways and back and forward. One of the news people rode it along with one of the manufacturing people. The news guy looked ill at the end. It is not going to be for the faint of heart.
At the time, I wondered if they would theme this to do with a quiditch match. The visual that you look at while moving could make you feel like you were part of the game. I'll never ride it, but it does sound cool!
I'm VERY excited about it, but not planning a special trip around it. I think I'll wait until the initial crowds subside (sure it will be regularly crowded forever!)
I've always wondered what Butter Beer would really taste like!