My son did one during either SDCC or Blizzcon one year and said he got nauseated. I guess the fault was on him because it has to be like crystal clear or sharp and he said it was when it wasn't completely. If that makes any sense, lol.
Whatever he did, it wasn't this experience. It only opened in Anaheim on January 6 and it is a permanent installation in Downtown Disney.
That being said, there have been many VR demos at SDCC offsites, and I can believe that they would make people ill. They are very realistic!