They call the AMC IMAX screens LieMAX because the screens are so small. I went into one once to see The Dark Knight and the screen was comparable to one you'd find in some people's homes. It was ludicrous.
The new digital projection we have at the 8-story tall IMAX near my house looks brilliant and is still capable of the full IMAX picture format. I think it was the trailer for Guardians of the Galaxy that had some scenes in the full format size and it was breathtaking. It's so big the film engulfs you.