IMAX is a very large curved screen that immerses you more into the experience. When you couple that with 3D it is from my perspective the best way to watch an action film. Some folks even get a little motion sick so be warned.
There is another large format out now as well. Just a larger screen & better sound that you can catch at Sandhills. I believe that there is an IMAX now at one theater in Irmo but not sure.