Seeing a film in an IMAX cinema means significantly bigger screens, incredible sound, and in some cases (including Oppenheimer) more vertical information on the frame (with the essential components remaining in the standard 2:35:1 aspect ratio seen on regular cinema screens). Also, IMAX 70mm is even better, but there are only a handful of those in the world (here in the UK, its a choice between London or Manchester if you want to see this in 70mm instead of standard digital).