Ebert's point on focus really hits home for me. When you are watching a movie in 3D it feels like I should be able to focus my eyes anywhere I like, instead of accepting the focus the director has chosen in traditional movies. When I want to look at something in the background in a 3D movie, I expect to be able to focus on it. So either all 3D movies need to be filmed with really high depth of field, or 3D will always feel broken.