Bad, one of the most regrettable manhwa I've ever read.
First, the MC is dumb. She act like a child, even after the timeskip (maybe it's reasonable because that might be the cause from childhood trauma when she was pink eye) even though it's quite reasonable enough, it doesn't make sense because she has her past life memories (it would've been better IF she DOESN'T have her past life memories)
Second, the whole character development is dumb and stupid. The MC acts like a child, but when her father went to fight the dragon and she needs to lead the war she decided that she needs to be more mature, after that she changed her clothes from childish outfit to more mature and ladylike outfit and because she changed outfit her personality became more matured (r u serious? Different clothes/outfits doesn't change one's personality). The male lead's personality is shitty, and he didn't even tried to change it. The whole thing with the MC's family feels unrealistic, how can you accept a sister or a daughter easily and just like that?
Third, the personality of the characters. The MC is naive and selfish, she found out the truth about the shitty personality of the ML but she ignore it when the ML said sorry to her (she doesn't try to change his personality because he never did that to her, how can she ignore the victims of the ML's violent personality when training?). The ML's personality sucks, more like a yandere (I don't really mind yandere, but at least develop your personality more to be a better person) and he holds too many secrets. The father's personality is weird, I get it that he's a loving father but shouldn't he act more cold to his new daughter (then the daughter tries to gain love from him, that'll be more cliche but better storyline) and he doesn't grow old at all (he's appearance remain the same without wrinkles and white hair after timeskip). The brother's personality is fine, but when he met MC for the first time he was mad because MC went to his room. But when he found out that she is his sister, he became nice and became a siscon.
Fourth, the relationship between MC and ML. They said that the age gap was not too large and the reason is that the illustrator made the ML looks older than he actually is, but for me no matter what the reason is I think it's still too large of an age gap. I don't mind age gap (if they met when the MC is an adult), the thing is they met when MC was still a child (looks five to me when she first appeared) and the ML was a teenager to and adult (looks 18-20 to me when he first appeared). The ML was already a grownup knight and bodyguard! And the MC was STILL A CHILD!! I'm sorry but this is quite mess up, it's okay if they met when the were a bit older (but NOT OKAY when one of them met when they was still a child and the other was still a teenager)
THIS STORY MESSED UP REAL BAD! I'm sorry for a fan, but I merely stating my opinion regarding the story I've read.