My book club is reading the Josephine trilogy by Sandra Gulland, which is a historical romance written in a diary style. Not at all my type of book.
(I prefer sci fi romps with political undertones where the bad guys get told off scathingly before they die.)
And yet, it's really good. Believable. Intriguing. The villains are strangely charming and likable. Josephine is a kind person trying to keep her children safe while taking enormous risks to help others. Napoleon is scrawny but still kind of hot, with his cold grey eyes, huge personality and complete lack of humor.
The worst people in the book are Napoleon's immediate family. I hate them. I want to slap them upside the head. Whereas I have a sneaking fondness for the architects of one of the most monstrous civil wars of all time.
Everyone is in debt, everyone socializes with murderers, everyone is feckless and desperate and yet... you gotta like 'em.
Now, that's good writing.