It's HBO, of course it's going to be cinematically good. The problem is what it depicts and how. It is utter schlock in that regard. Lies, lies and more lies about "muh evul soviets and their shitty reactors and stupid people living oppressed and ignorant".
It's irritating as fuck just for the anti-sovietism, and outright LIES about the majority of details and many events.
The only commendation I can give it is as an effective piece of anti-communist and anti-nuclear propaganda that has solidly scared a large portion of the West into being scared of nuclear energy and commies again.