I think I agree with Craig Mod about wishing that it was more a story about the birth of the atomic bomb rather than the story of Robert Oppenheimer specifically. I read Rhodes's The Making of the Atomic Bomb back in my twenties at some point, and it, along with Mukherjee's The Emperor of All Maladies, are the only two books I really remember from back then.
Still—Oppenheimer was great! I think that given the direction that Nolan decided to go with it, he made the best movie he could have made.
I think that Oppenheimer's many infidelities could probably have taken up a bit less screentime—by the end they're numerous enough that they barely get acknowledged—but it's a character study, so I suppose it's to be expected. Not being acquainted with Oppenheimer's fall from grace directly after the war, I was expecting that the political drama would end in disappointment, but I was glad to see that Oppenheimer was, at least nominally, politically rehabilitated (Soviet style!) much later. Downey Jr.'s Strauss was fantastically acted, but the twist-villain thing in the third act felt a little rushed.
Something I hadn't heard much about before seeing the film: the sound was absolutely fantastic! See this in theatres if you can. I guess I could have expected this of Christopher Nolan, but the dynamics of quiet and roaring noise addedso much to the inner turmoil of Oppenheimer's relationship to the gadget he created.
Not a complaint so much as an observation: I would have watched like a further five minutes of the Trinity detonation, if Nolan had really liked slowed things down and given us the nanosecond by nanosecond on the first detonation. Maybe fetishising nuclear apocalypse like that is problematic.
And a final observation: Jason Clarke's Roger Robb kept saying nucular instead of nuclear and it drove me right up the wall. Knowing Nolan's eye for detail this was probably intentional.