Chernobyl is a fine example of a dramatised documentary - it has excellent acting, accurate (for the most part) period reenhancement, and takes only a few liberties with historical facts.

Just as important, I think, is its ability to explain what went wrong in a nuclear power plant in 'layman terms'. And it does not use the platform to pass any message (though it is easy for the viewer to contrast the Soviets' ignoring of the problem with similar modern attitudes), which would be ill-placed in a show dedicated to a historical event.

That said, I do find its incredible popularity and rating a bit puzzling - it's really good, but wow. At least it gives Jared Harris his due, he is a superb actor (though I liked Paul Ritter even more here)