I’ve identified the reason my husband loves this series and it because El, the main character, is grumpy and curmudgeonly and RELENTLESSLY committed to doing the right thing. The drama in the series comes from the story of a good person who struggles to be good when being evil is always easier choosing to be good again and again. It’s kind of brilliant and also deeply fun to watch goodness spread like an ideologically transmitted infection and it works. 
It’s ALSO another story about the trauma  of being the hero in the same vein of Rowell’s Carry On trilogy. If El is basically the redemption of the Slytherin, Orion is the trauma of the chosen one when there’s no one left to fight. Novik handles it very differently from Rowell, not just because she’s interested in telling a very different story, but also because this book isn’t inherently about what comes next. I’m fascinated to see what the next one does.