Honestly, I wanted to make a slightly in-depth review for this, but I've seen a lot of extremely good reviews posted already; so instead, I'll try to make it short and simple.

I have absolutely no idea why some people are calling this overrated. It was definitely being talked a lot about within the community but outside the MDL community, almost no one knew about this drama. The cast wasn't your typical mainstream household names, so non-avid watchers weren't swarming to watch this drama and join all the hype it was creating. Flower of Evil definitely isn't overrated. I honestly wanted this drama to garner even more attention than initially gained.

This is exactly what I was looking for in a genre like this. I often found myself at the edge of my seat losing my breath as I didn't want to miss a beat in very intense scenes. I kept asking myself "HOW??", "THEY'RE ACTUALLY DOING THIS??", "THE WRITERS DID THIS THIS EARLY??" in the majority of the drama. This drama will keep you second-guessing, and it's what makes this drama so fun; you're never too sure of yourself.

Flower of Evil is a masterpiece. It is definitely a very interesting drama to watch. What more can I say?
Last words: Unexpectedly heartwarming
Everything was somewhat... poetic in a sense

edit: the ending? not so sure about my thoughts about it. I can't wrap my mind to it if there could've been a better one.