The rear seats are quite comfortable. My Wife and two boys sit back there and they have no problems whatsoever.
BUT......................................
This happened to one of my friends once. We were on a one hour drive to view a site. He was sitting in the back watching a movie. Apperantly watching a movie and being in motion, for him, made him nautious and dizzy.
It's possible. Rear seat home theatre is not that popular yet.
ICEMAN,
Your friend knows alot of H2 owners? Or mabye he was a back seat rider in one. Some H2 back seat riders get sick with envy
...It could happen!