Oh, interesting! It's not so much that I get a headache, but the vision in one eye has been significantly weaker than the other one for so many years that apparently my brain has stopped seeking equal feedback from it - which in the theatre means that I'm stuck with the odd feeling of looking through my eyes separately, negating the 3D effects.

I suppose if the fad continues (and if they ever stop charging an extra $3 for the "privilege" of 3D), I might have to try out something like this.