Oppenheimer is a great movie because its story was well crafted from the book, “American Prometheus”. Nolan had a great and complex character to work with, a perfect goal (build the bomb to end the war), and a tragic aftermath when Oppie’s leftist sympathies opposing racism and fascism in the ‘30s, became grist for his political enemies in the McCarthy era.
It wasn’t brought out in the film, but he realized he had been a useful idiot regarding the Russians when they totally dismissed his efforts to negotiate nuclear arms controls after the war.
What I didn’t see was the purpose of using 70mm. It was interesting for some of the bomb test scenes, but superfluous for most of the lab dialog and the clearance hearing scenes. It may have been something Nolan likes to work with, but it didn’t add to the great story enough to justify its expense or complexity.