Film Temet Nosce
The most cogent advice I can give about whether or not you'll enjoy Oppenheimer is simple: if you don't like non-linear storytelling, you probably won't like it any more than you've probably liked any of Nolan's other films, so don't bother. If you're a prudish American like me who's not too keen on nudity, it does serve an artistic purpose here beyond "creative likes bewbs," but you might be well-served by taking a strategic bathroom or refill break during the relevant portions of the film if it's a bit much for you. And If you just don't care much about long, serious historical dramas, well, I don't watch bloodbath slasher movies and then complain about idiot teenagers gettin' cut up just because the subject matter's not my thing.
In that vein, Oppenheimer is the story of the men who built the atom bomb, before during and after that fateful moment when a bunch of uranium explodes out in the New Mexico desert and puts humankind into a new and frightening era. All the actors and actresses are giving it their all, the script presents more twists and turns than you'd expect, especially in the flash-forward parts of the film set in the midst of the post-war era, and the special effects are used properly to heighten the drama and story rather than getting lost in their own technical achievement. It takes a lot to make an explosion look impressive in this desensitized age, and the detonation of the first atom bomb had my theater speechless.
Sadly, I also feel the need to add that at least in my theater, there weren't huge problems of sound mixing drowning out dialogue that previous Nolan films have suffered from, but I have heard reports that this is not a universal fact.
Beyond that, I can see the biggest obstacle here being the thick and fast maze of important early 20th-century physicists the film throws at you. After many years of varsity academic team in high school, I actually did know who a fair few of these scientists by achievement without knowing who they were as men, and that did make the film pretty gripping, but without that background I might've gotten lost. If that sounds like a humblebrag, well, I've worried about how to articulate the one without the other basically since realizing the film was really throwing those scientists at you, but hey.
Again, Oppenheimer is a really good movie of its kind, and if you're up for it I do think it is a very rewarding movie of its kind. But I can see it not being for everyone too.
Film A taut and engaging biographical drama
Oppenheimer is, quite bluntly, not a movie for everyone — there are no major action sequences or eye-popping visual effects to appease the masses, no joke-quipping sidekicks or goofy animals critters to placate the kids, no gushy romantic subplot or sentimental nostalgia to give viewers the warm fuzzies as they munch their popcorn and slurp their sodas.
What we have here instead is a three-hour-long look at J. Robert Oppenheimer, the father of the atomic bomb and the man who forever changed global warfare. While this sounds like a dry historical piece for wayward documentary fans, Oppenheimer is anything but — I was delightfully engaged and riveted by the movie, watching Oppenheimer constantly torn between his desire to defeat the Nazis, his thirst to push the boundaries of physics, his personal left-wing sympathies and naive idealism, and his resignation that his work will most likely make the world a more dangerous place. Throw in his womanizing tendencies, his obliviousness to the political gamesmanship whirling around him, and the machinations of others around him, and Oppenheimer ends up as a captivating character study as we watch this man being tossed about by his inner and outer demons.
The thing that makes Oppenheimer such a captivating film is that it is all deceptively easy to follow. While Christopher Nolan infuses Oppenheimer with extensive use of flashbacks and call-backs, they don't interfere with the story flow at all — just keep your eye on the man himself and watch the chaos swirl around him. Similarly, despite the heady subject matter, there's no need to have a deep background in science or history to enjoy the movie, as relevant issues are effortlessly introduced and smoothly explained without ham-handed exposition. Similarly, the All-Star Cast doesn't overwhelm the film, which allows each character to be distinctive in their own way, and judicious cinematography and direction draw the eye without overwhelming the viewer. The end result is a brisk three-hour Biopic that keeps your interest throughout and is richly rewarding as a result.
Again, Oppenheimer is not a movie for everyone — if you're looking for simple entertainment or a casual distraction, you'll have to look elsewhere. What we have here instead is a memorable visit into the life and tribulations of a man at the center of one of history's most important milestones.