I know a common complaint is that in this drama they’ve added things that weren’t originally in the webtoon but honestly these things gave some of the characters more depth that they previously lacked in the webtoon, especially Suho’s character (which I actually wasn’t a fan of in the webtoon but absolutely love in the drama). In the webtoon the female lead is always hiding bare face, even after she graduates high school she's still paranoid and hiding her bare face from people, so its a nice change of character in the drama that they make her gradually more confident both with and without makeup to the point where she's even stranding up to her oppressors.
The webtoon wasn't complete when they filmed this and the author did come up with different character endings from the webtoon. But the story of an insecure girl that goes through some sort of beauty transformation has been told many times before and it’s nothing new as is the typical love triangle but if you enjoy those traits then True Beauty will be very fun and entertaining to watch.