So it seems the mangaka has made some changes to the original story that makes more sense, so it shows the mangaka is at least aware of some of the issues with the story. But even still, there are so many issues the story fouls often and heavily regardless, and sometimes it does worse than the novels anyway.
Pacing is inconsistent and blistering, the plot just... plots, and the characters are poorly written.
The villains don't have a reason for being bad, and at least one of them makes no sense whatsoever. I'm not even kidding, I don't know what the villains wanted, or why they became villains. Here's what I do know, based on the information provided by the manga (minor spoilers):
The king and the prince have the same goal even if the story pits them against each other and neither of them know it.
The knight sometimes wants to be a knight, supposedly has a harem, cares about his job and then doesn't, and then says he wants to be king even though he's helping the prince take the throne that will be his in a few years if he just waits.
Noel's childhood friend, the saintess, apparently can't stand not being royalty and living the high life, so she got with the prince, is carrying his baby, and is going to marry him soon (until that all falls apart and she's sent to the nunnery as punishment). But wait, isn't the prince maybe trying to give up the throne? Why would she support that?
Noel cares for no one. He's a boring, emotionally dead, contradictory character... which is par for the course here.
And yeah, that's it.