Properly calibrated 3D is awesome and brings a film to life
I agree with this. Out of curiosity I compared the opening scene from Life of PI in 3D and 2D at the weekend (not than I am a fan of the film). The former was far more involving. (I didn't compare the big set piece scenes where the difference might be even more marked.)
I can inhabit a 3D film in a way that is not possible in 2D. However, it is certainly not the case that every time I want to watch a film I would countenance putting on a pair of big awkward glasses over my glasses! It can be quite tiring. Nor put up with my noisy ceiling mounted projector in 3D mode (something I must sort out if possible.)