I saw this film last night and thoroughly regretted going. The film is a disjointed tangle of dialogue scenes with nearly constant pre-crescendo trailer music throughout played far too loudly. It focused hugely on things I simply did not find interesting such as his mistress and a prolonged and - again - boring investigation into Oppenheimer himself. I fell asleep in the first hour and was annoyed to be woken up periodically. The film consists hugely of disconnected, colour /b+w threads which don't inspire or interest. I have never looked at my watch as much during a film. Had they been handing out free DVD copies of the film or free tickets to see it again afterwards, I would have refused both. I was a fool to believe the hype and I offer my thoughts to perhaps spare some other unsuspecting fool from being sucked in. 3hrs could have been compressed into 1 tedious, poorly entertaining hour. The music and the nuclear explosion scenes were also profoundly disappointing. If you are going for any kind of interesting insight into the A-bomb development or the dropping of the bombs on Hiroshima and Nagasaki then don't.
A terrible experience overall and I would tell my pre-viewing self not to bother.