We saw Oppenheimer at our local cinema. I was glad I saw it in the theater because the Trinity test alone warrants that experience. I was mildly disappointed that the only showing in the "RPX" auditorium (which has noticeably better sound) was after 10:00 at night, which was not an option for us because the movie is just too long—I wouldn't have been able to stay awake. It's also unfortunate that the Uptown is no longer open to show that one. The bigger the screen, the better, and let's be realistic, most screens today are far smaller than the huge ones many of us grew up with.
I would have liked to have seen it in the IMAX 70 mm format, but the nearest theater that has that format is in King of Prussia, PA, and I wasn't going to drive that far.