I saw this movie in Imax 3D and it was fantastic. My wife wasn't sure about this movie after watching the previews and came with a "along for the ride" attitude. After it ended, these were her first words: "WOW, this was a lot better than i thought, those previews don't do it justice."
I would recommend AT LEAST an IMAX screen, the effects are great and you will want to see all of the detail. If you have an IMAX 3-D, this is my format of choice, not for all movies but movies like this one only don't come around often.
If you are unsure about this movie, give it a chance and go watch it. If you want to see this movie, then stop reading this and get to the theater.