This is a great film, but let me clear something up from the other reviews.
It's not all in 3D and its not all in 3D once they enter into the digital world. The 3D scenes are entered into the film throughout and you can tell when because the aspect ratio changes (ie the black bars disappear). That is because these are the scenes that were filmed for IMAX 3D.
There is approx 40 minutes of 3D footage during the film most of which adds depth but don't expect too much pop out 3D.
I rented the movie in 3D to see if it was worth upgrading, but overall I would say no and will stick to my 2D copy.