Seconded, thirded, whatever on the FOV problem. Headache guaranteed there.

The problem is that dropping the use of depth-of-field removes the most powerful tool in a film director's arsenal for getting the audience to concentrate on the bit he's trying to emphasise. It's also nigh-on impossible for live action to film with a depth of field permitting everything between the camera and infinity to be in focus in all bar the strongest light levels.

The other snag is they'd have to either shoot the film twice or post-process the 2D version to add the depth-of-field effects. Presumably post-production depth-of-field for 2D would look about as good as 3D conversions on 2D material do. I.e. Shit.

Works well for animated features though.