(edit just in case: SPOILERS)
As a fan of the webtoon, the webtoon ofc establishes the characters and their motivations much more clearly and in a timeline that makes more sense. I haven't read the web novel so I'm not sure how much they pulled from there vs the webtoon. But I'm honestly unsatisfied with the changes they've made to the story at least from what I've read and known from the webtoon. It feels like they watered down a perfectly good plot and characters into something much more generic. Like the source material was great, handed to them on a silver platter, and they chose to make unnecessary changes like adding in this rival (Yura) for Jiwon, watering down Jiwon's character into someone much less resolute or ruthless with her desire to really take the reins back on her life, involving Eunho much more than needed to in order to exacerbate the "love triangle", taking away the accomplishments of the other FLs such as Juran and putting them all on Jiwon instead, etc.
It just sucks because it's honestly a nice empowering narrative of independence and confidence in yourself and your choices, while also still sharing a message of the power in not being alone and being able to truly depend and have people who actually care for you. But all this was kinda watered down into a generic revenge plot.
EDIT after watching the last ep: I think they did redeem themselves more for not changing the super major plot points though (like the people who were supposed to die died (except for one character due to Yura's character being put in this lol). And they kept the ending much more accurate and happy! Honestly, my feelings on this was 'it's not about the journey but the destination' LOL which is usually the opposite for me.
All that said, while I highly recommend the webtoon, the kdrama might be a hit or miss especially if you're watching this coming from the webtoon.