This series is really excellent. As any other series based on historical persons and events, it's a mixture of facts and fiction, and I'm totally okay with that, as long as the fictional parts don't wander off too far from what really COULD have happened. The story of Catherina de Medici's life (here pictured until the death of her first son and herself becoming the regent of France) is exciting and involving, the settings are beautiful and authentic, the costumes luscious, and the acting of all major parts is great. With special mention of Samantha Morton, she is absolutely brilliant as the scheming, highly intelligent and outwardly ice-cold Catherina, who still at a few times poignantly shows her inner emotions.
I still had a few minor reservations. The makers made Catherina and a few other major characters by means of a voice-over the narrators of the story, for me this didn't really add anything (unless at times some confusion as to the chronology), and they also let these characters at several unexpected moments step through the fourth wall to directly address us viewers, for which I didn't much care either. The dialogues of especially the male characters (the Bourbons, the Guises, Montmorency) had a very nowadays and thus a bit of an anachronistic ring to them, for instance the profuse use of the F-word in every other sentence. And the at times rude and condescending way with which some courtiers and members of the Privy Counsel addressed their royal superiors seemed to me rather improbable in those strict hierarchy-centered times.
But for the rest: a riveting and visually beautiful series, I can hardly wait for the second season!