I can't really say whether 3D films can ever work, because they don't work for me. However, if Ebert is referring to post-production 3D like Green Hornet and Alice in Wonderland, he should probably be aware that even proponents of 3D think that the post-production stuff generally sucks.

I also thought the guy's argument that 3D is less immersive than 2D films to be kind of dumb. It would be one thing if he were arguing against the notion that 3D is more iimmersive, but he's actually saying that 3D is less immersive than traditional 2D. I don't think that's true. They're probably equally, if anything. As if being "immersive" ever had any meaning anyways.

He does make some good points there, though. Personally, when I go to the theater, I'm not going to want to pay extra money for a headache-inducing darker picture and an effect that doesn't even work for me.