There must be a lot of people who get sick on it, as they now are handing out barf bags! We however (me and 3 kids) had no problems with it. DH chose not to risk it this trip, as Astro Orbitors turned him green for hours! He has said he will try it in January.....
The first time we rode it I was a bundle of nerves. There has been so much hype over how it can be aweful for some people.
My personal strategy......
first off, keep your head back, and eyes open as recommended. That is a MUST. However, if you begin to feel dizzy or disoriented, I would suggest focusing your eyes downward at your joystick rather than out your "windshield" screen. Don't move your head, just shift your focus to something that doesn't appear to be moving. You'll still feel the G-forces, but it lessened the dizzy factor for me.
Second time I rode it, it was phenomenal! I watched the whole thing - including lift-off and the "sling shot" around the moon that I couldn't watch the first time. Definitely it's not for everyone, but I thought that Body Wars was MUCH higher on the "illness scale" than M:S!