In a letter written to Ebert by Walter Murch (in Ebert's words, "the most respected film editor and sound designer in the modern cinema"), the editor proceeds to eviscerate the merits of 3D technology:
The biggest problem with 3D, though, is the "convergence/focus" issue. A couple of the other issues--darkness and "smallness"--are at least theoretically solvable. But the deeper problem is that the audience must focus their eyes at the plane of the screen--say it is 80 feet away. This is constant no matter what. But their eyes must converge at perhaps 10 feet away, then 60 feet, then 120 feet, and so on, depending on what the illusion is. So 3D films require us to focus at one distance and converge at another. And 600 million years of evolution has never presented this problem before. All living things with eyes have always focussed and converged at the same point.Murch goes on to explain that we "can" focus on 3D films, but "it is like tapping your head and rubbing your stomach at the same time, difficult," invariably resulting in instances of moviegoers getting headaches 20 minutes after a 3D movie begins. "This is a deep problem, which no amount of technical tweaking can fix," he figures, before listing off the negatives of 3D: "dark, small, stroby, headache inducing, alienating. And expensive."
The solution? Nothing. Until the time that "true 'holographic' images" are produced, at least.