I saw it in IMAX and it was a big disappointment. Very few theaters showed the movie as projected IMAX FILM, a process that runs 70mm film sideways through the projector making for a huge negative with very low grain and incredible resolution and clarity ( VistaVision with 70mm film rather than 35mm). Most IMAX theaters, including the one I saw the movie in, merely digitally project the picture. In effect you're watching a giant 4K TV, big deal. The picture had digital artifacts and looked washed out. It will probably look better as a Bluray disc on my home TV.
And even had the movie been shown on large format film it lacked the kind of scope and vision that made the large format roadshow movies of the 1950s and 60s such a visual treat--think Lawrence of Arabia, El Cid, Ben Hur and How the West Was Won. Oppenheimer would've worked just as well, if not better, had it been shot in black and white on 35mm film in the old Academy ratio. With mono sound.