When it comes to 3D movies and content some people just can't stand the stuff. This isn't always just because they aren't fans of 3D; some people really can't watch 3D content without getting sick. I know a few people who never see 3D films because they get dizzy and feel bad. Reports are coming in that Nintendo held a showcase for the new 3DS console in Japan recently and journalists covering the show claim that some people got ill from playing the 3DS.
One of the publications is called Friday and is described by Kotaku as a tabloid. According to the author of the story in the Friday publication, several people using the 3DS at the show complained of feeling ill. In fact, the author of the story in the tabloid said he felt "seasick." Friday wasn't the only publication on hand that noted some folks felt sick.
Nikkei was there and did a video interview with one user who complained that after a minute of play, his eyes felt "tired", but he noted he could "bear it" and kept playing. I would say that 3D on the 3DS will be no different than 3D on other mediums and will cause some folks discomfort.