On one level it's exactly as you'd expected a teen aimed CW production to be. The cocktail gowns! The hair! The pop songs in the soundtrack! The utter disconnect from anything resembling historical plausibility! Seriously, the sheer crackiness is awesome. S1, apparantly having decided that Catholics versus Protestants is boring, has this entire subplot about secret pagans, and Mary Stuart, of all the people, spouting such lines as "We're not judging you for your religion". S2 does go for the actual big religious conflict of the era, but doesn't bother with such minor things as actually explaining what the differences are, beyond "no Pope". Young Mary Stuart is still a champion of interfaith tolerance, pleading the Protestants' cause (this is hysterical; also, she'd have been incredibly insulted if anyone had told her back in the day she'd ever been depicted as such), and the only Guise relation of hers to show up, other than her mother, is of course not the leader of the hardcore Catholic party more popular than the Royals but Some Guy Easily Disposed Of. (Don't I wish, says the shade of Catherine de' Medici.) Philip II. of Spain gets married to Elisabeth de Valois in the pilot while Mary Tudor is still alive throughout most of the first season. (Philip was a bad husband to poor Mary, but bigamy he'd have drawn a line at.) The Bourbon brothers, Louis, Prince Condé, and Antoine finally make an appearance in s2, where Louis gets to be Mary's temporary love interest and a possible candidate for Elizabeth I. to marry.) (Imagining how both their historical counterparts would have reacted to that suggestion is hysterical again. Good old Condé's historical wives whom he got, all in all, eleven children are of course non existent.) Reign is one of the few historical fictions to actually use Claude, Catherine's second oldest daughter, as a character, but whereas historically she was the only one of Catherine's kids not to have scandalous rumors attached to her and being her mother's favourite, here she's a a teen version of her sister Margot's popular image as a rebellious good time girl and her mother's unfavourite. (Margot has yet to be mentioned as existing, btw; of the younger kids, we've only seen Charles though the future Henri III. was mentioned in dialogue as well.)
Then there's the part where the French court keeps residing in "the castle", which isn't in Paris but isn't one of the gorgeous Loire chateaus like Chambord, either, instead being near the sea coast and looking grey and gloomy. The English, independent of monarch, are Up To No Good throughout but strangely never use this golden opportunity. In s2 inquisitors and their thuggish helpers, directly employed by the Vatican, roam the countryside to round up the helpless, hailing directly from Hammer Horror movies, but the French court itself, other than the occasional Cardinal visiting from Rome, is strangely cleric-free And so forth and so on. When, in s1, Henry II. in a rare reflective moment mentions having been a hostage as a boy it was an utter shock to this viewer because unlike most of Reign's other events, that actually happened.
If you utterly disconnect the goings on on screen from any historical knowledge of this world and see it as pure fantasy, a la The Enchanted Forest in Once upon a Time, though, it definitely delivers in the "entertaining soap" category, and it offers not one or two but five regular female characters (Mary Stuart, Catherine de' Medici and Mary's ladies, with the sublimely historical names of Lola, Kenna and Greer), whose developments and exploits we're following. Plus recurring female guest stars. The Catherine-Mary relationship starts in classic villainess-heroine manner but turns into something surprisingly complex, and Catherine herself is a great character, giving me fond flashbacks to 80s soap operas where the female antagonists if they stuck around long enough were developing layers and also nearly always got the best lines. As for the girls, their stories are actually quite good variations of "how to survive in a system that's stacked against you" even if they do so in cocktail gowns and blithely unburdened by anything resembling period attitudes. It's not every show, crack history or not, which is a female character turn down her True Love's marriage proposal because she's found she likes being financially independent and on her own better. (As opposed to turning it down because of misunderstandings, because of a rival, because she's pressured etc.)
Also, there's a lot of black humor in the dialogue. Have an example:
Mary and Catherine are in their annual "antagonists teaming up because of shared danger" episode; Catherine draws a stiletto, Mary perks up:
Catherine: You say that so hopefully now.
In conclusion, it's pure crack, but if you have nothing else to do and it's available, go for it. Just don't play any drinking games counting anachronisms and the like, or you're passed out before the first episode is even finished.
Meanwhile, in another fandom:
Apples: Joan and Evelyn backstory, sensual and poetical. Headcanon accepted.