Excellent - stayed close to the truth (having read many books about it), and did not use the Hollywood approach of making stuff up for "inclusivity" and "relevance" . Well acted, and it was good to see the actors use their own accents, and not try to do a daft James Bond-style Russian accent.
And a very clever twist at the end regarding the role of "Ulana Khomyuk".
I remember living through the horror when it actually happened - this series shows the utter incompetence driven by Soviet-style industrial practices. The best show on any channel in 2019.