There appears to be a sub-genre of Villainess anime lately.

The anime opens with a girl passing away from terminal cancer, clutching a handheld games console playing her favourite otome game, Regalia of Saints.
Said girl awakens in the world of Regalia of Saints having been rejected by Prince Cedric at the Ball.
She is Aileen, the game's Villainess; using her knowledge of the game, she decides to manipulate events in her favour starting by falling in love with the Demon Lord Claude, initially to avoid her own demise at his hands, the love for Claude becomes genuine as she learns about his side of the game; the whole plot shifts through three scenarios preventing everything from betrayal, sabotage and outright murder, Aileen will do anything to save Claude, but it soon becomes clear that she's not the only one who knows how the game works.
A true costume drama with all the trials and tribulations of many a trashy romance novel with all the fabulous fashion that comes with it, Villainess finds a good mix of a very well written main character in a world that doesn't give her an easy time with a twist very few saw coming.
It's a nice balance that's worth sitting through but there are one too many subplots and the cast could shed at least five or six characters that add nothing to the plot but distraction.
Not seen the dub but there are certain actors I expect in certain roles and I'm proved right so it's average.
Final Verdict: It could use with shedding a few pounds but it's hardly a deal breaker and the main character is definitely worth cheering for to the point where you forget it's an Isekai.