9 stars? Severely overrated. That rating is solely due to the shock factor and gimmick of its first chapter. The subsequent chapters have not been able to build on that momentum and lands flat on the ground. I've read up to 5 chapters (latest) and the main thing I want to talk about are three particular characters in the manga: the MC and the two princes.
As previously mentioned, this manga is overrated. Everyone was blown away by how the MC punched the Scumbag prince after the annulment. This is refreshingly new as the general trend is that the MC of this genre would've usually backed down quietly to live a commoner's life or build her way back up so she could face slap her enemies in the future. That's cool and all but that is nowhere near deserving of 9 stars at all. Not to mention since there are two other reasons why this manga deserves lesser stars.
There's the Scumbag prince who for some reason is a lot more retarded than the generic ex-fiance. And by some reason, I meant stupid reasons. It's a common technique in storytelling to have an obnoxiously hateable character to make you root for the MC but man, make it less pathetic. A royalty who calls her fiancee a servant on the first meeting? And the MC puts up with it? The scumbag prince is already pathetic enough, the fact that the MC put up with him inadvertently made her look pathetic as well. You could reason it out as biding her time or doing the logical thing, but that doesn't change the fact that she had to be pathetic and miserable for more than half her life at that point.
Now there's the "perfect" prince which in my personal opinion is a perfect example of the cancer that is called male lead in shoujo manga or novels. The author makes it blatantly obvious how talented and handsome and perfect this guy is that it's hard to stomach. It sends the idea that girls only want one thing and it's disgusting: handsome and talented hot guys. The way that he looks at the MC like some fucking toy is just intolerable. The strong point of the MC is that she's someone who is strong and independent, and yet she's being toyed around like a mouse? Laughable.
My biggest criteria when it comes to shoujo manga and novels is how likeable the male lead is. It doesn't matter how likeable the female MC is; in fact the more likeable she is, the harder it is to stomach how the author is trying to develop the romance between the two of them. Just by this reason alone, I would've rated this manga at 6 or below. At that point, I wouldn't have bothered reading the rest or even writing a review about it, but since there's only 5 chapters released and seeing how this is one of if not the highest rated Villainess novel in mangadex, I had to share my take on it. I'm guessing 1 or 2 volumes from now, the ratings would go down to 8 but 7 is unlikely. The pilot chapter got popular on reddit and most people rated in 9 or 10 and then quickly forgot about it. Even if they continued to read the rest, they wouldn't be bothered to change their first impressions, much less the rating that they gave. Overall, I'd give this series a 4-Slightly Bad and Dropped. I'm not trying to make you rate this manga less than 5 stars but before you rate it 9 or 10, please make sure to look at the romantic interests and judge if it really deserves to be labeled as great or masterpiece.