Firstly, I'll note that most of what is driving the poorer reviews on this site seems to be that it accurately portrays Trump's early career in an ungilded light and a lot of people are upset by the truth of it. If you know anything about his life and what has been reported by friends, family and others, there is little in this film that will surprise you. Despite the claims of Trump's more ardent supporters, it has no need to be a hit piece - merely presenting the reality suffices.
That said, despite Sebastian Stan's spot-on performance (one can see so many of the little mannerisms that modern-day Trump has developing), it's Jeremy Strong's Roy Cohn that is the mesmerizing figure in the film. Strong's dead-eyed fixer (but self-professed patriot) really drives this film, and every scene with him in it crackles. Sadly, the scenes when he's not there feels a bit limp, although that is no slur against Stan. Strong really ought to be an Oscar contender here.
Maria Bakalova does a similarly sterling job as Ivana, although very much a supporting player in this Trump-Cohn story. One comes away with the understanding that she was a driven and ambitious businesswoman herself, but one with more humanity than her husband. (And it's best not to think about how she ended up - it will just make the whole thing even sadder).
Again: if you know anything about Trump's life, this is unlikely to tell you anything new. But it does fit all the pieces together into a narrative that explains quite a lot about the man he is today. And if you can take even more about Trump than the daily news provides, it's worth watching this just for the performances.