Oh my god, once you have enough free time, definitely watch it.
The tension and suspense in some of the scenes where the Geiger counters start to tick violently are honestly more terrifying than a lot of horror movies, and the fact that this actually happened in real life just adds to it. The sudden radiation burns and effects on the people at the start is also quite horrifying, the slow deterioration of the firemen is even worse. Amazing soundtracks have also been used in this, adding more to the suspense or highlighting a moment of sadness. They also focus on a variety of different characters, from the reactor workers themselves, to the people who solved the entire problem, to a fireman's family, but they still manage to somehow keep each character quite interesting.
I literally cannot even express how realistic this series is. The solutions to the problems are very scientific (at least it sounds like it, I haven't looked into it but people have said its very accurate). They explain how a nuclear reactor works, how the RBMK reactor could fail, how the accident happened, the spread of radiation and its effects and so much more. I recently watched a video comparing videos from the real life Chernobyl disaster back in 1986 to the scenes of the series. The scenes almost look identical, apart from the camera angles, but every scene is meticulously arranged to look like the real life accident. There is one character that is completely fictional though, but she is a big part of the story.
What's even more interesting is that it not only displays the Chernobyl disaster but it also highlights the faults and truths of the Soviet union.