Ahh where to start? I have mixed opinions on this drama. First of all, I did read the webtoon, but I didn't want to spoil the webtoon by watching the drama first nor spoil the drama by reading the webtoon first, so I read/watched simultaneously. I shouldn't have worried: the two are vastly different. You won't give much (if anything) away by reading/watching one at a time, they are that different. I liked the female characters better in the webtoon, and the male characters better in the drama. I couldn't relate or feel sympathetic for Shihoo in the webtoon but Lee Jong Hyun's portrayal of Shihoo in the drama ripped my heart out and stomped on it a few times. The main male lead Jae Min was even more likeable as played by Yeo Jin Goo than the webtoon version. I know some would disagree with that but here's why I feel this way: To me, Jaemin in the webtoon was almost bipolar in his actions. Hot and then cold (back and forth from the extreme of being a complete stalker to not being able to stand the thought of Ma Ri) at the slightest provocation. I felt the extremes in his behavioral swings were unrealistic in the webtoon, but the drama dowplayed the extreme-ness a little bit, making the character of Jaemin more realistic. The downside of this was that he appears to have less noticeable character development during the course of the drama. Straight up comparing his first episode behavior with his last episode behavior you can see a change, but over the entire drama it's barely noticeable. The webtoon Ma Ri as well as her various friends and enemies however, were all so bland in the drama compared to the webtoon. Ma Ri for example was more bold and plainspoken in the webtoon, but in the drama she was not like that until the end; in the beginning she was a timid, shy, and cowering. I don't have a problem with a female character who isn't loud, bossy, and outspoken personally so it didn't bother me. I'm not one of those females who looks down on other females who have a "quieter" personality, but I'll admit that for the sake of dramatic effect I liked the dynamic of Ma Ri's don't-care attitude in the webtoon and kind of missed it in the early episodes of the drama. I liked the storyline of the drama better than the webtoon, especially the addition of the historical backstory, though it was a bit disconcerting to be watching a modern highschool drama for 4 episodes, then a historical drama for 5 episodes, then a modern highschool drama for the last 3 episodes. Halfway through the historical episodes I wondered if I was going to remember the modern storyline well enough to know what was going on when they switched back. Thankfully there were flashbacks to help reorient the viewer to the modern storyline so that wasn't a problem. If you don't like historicals, you could probably skip episodes 5-9 and still not be *too* lost for the ending. A happy ending, for most of the characters, by the way.
I will warn you that the comments on this drama were exceptionally obnoxious. Repeatedly asking if the comments are a live chat. (No but wouldn't that be nice, then the annoying comments would actually eventually go away.) The people (there were so many of them) who somehow missed that JaeMin is the male lead (HOW do you even miss that?!) and thus is destined to end up with Ma Ri, and decided that if they whine and complain loudly and obnoxiously in the comments then Ma Ri will wind up with Shihoo instead... They even went so far as to bully and hate on the young actor Yeo Jin Goo in the lowest and most classless manner as though being hateful would change the story. Then there are always the perverts who just say gross things for no real reason, and those who spend endless portions of the drama arguing about what other Korean celebrities the actors each supposedly look like. If you are a Drama-Vampire then keep the comments on, you'll love it. If you'd rather watch it in peace however, I suggest you hide the comments. ;)