The first half of the movie is kind of less engaging and hard to keep track of. But eventually everything’s put into perspective. The movie is about Robert Oppenheimer and not about the atomic bomb. So we see the subjective pov of Oppenheimer, his feelings, dilemmas and epiphanies. And the ending is perfect and worth all the long hours spent. It doesn’t give a judgement or an opinion on the atomic bombs and also does not focus much on the bombing itself. But rather we see what Oppenheimer faces in the midst of power hungry political entities who manipulates people to pursue their selfish agendas.