They even record the music that scores all those action scenes live, in a studio, with an orchestra made up of living female and male musicians! Paul Englisby is the compose and music director. There aren't that many series that do this, not in the movies, even on Broadway, and certainly not on television.
There is nothing simple about Musketeers.
Even the super villain character of Milady de Winter is fully rounded, and complex, mysterious -- and developing. How can a villain develop? Their job is to be evil and thwart our protagonists. Even the primary villain of this season Rocheford, isn't simply evil, but boy, is he scary! King Louis XIII, lost much of his sympathy as he reverts to the arbitrary use of a monarch's power while becoming paranoid and very selfish with it, and thus easily manipulated.
All of these characters are equally interesting and were from the first episode of the first episode. They only became more so in season 2. So I'm very sad that Milady will not seen during the first episodes of season 3. Maimie McCoy is pregnant and was't able to join the cast when shooting began for it back in April.
The series even does women and people of color right, and within historical context. That Constance sees so clearly what the consequences up the line for her would be by running off from her husband to live with d'Artagnan -- and then they were able to get married, but not that fast, because Constance feels guilty about her husband's death, though in truth she wasn't responsible in the least. Though she did not love him she never pretended that it was right to be so passionately involved with someone else while married to him. It wasn't -- honorable. Though they marry and d'Artagnan is dazzlingly happy, it doesn't seem that he understands even now why Constance didn't immediately fall into partnership with him when Bonacieux was dead. He seems to believe she merely saw he was right and she was wrong.
And it's an adult series in which substantive matters are at stake -- though surely non-adults must find much of the program appealing?