The Elements of the story
This is the ultimate star crossed lovers story. Mix a boy with a mysterious past with one slightly crazy/very possessive twin, and a love that can never be, and you get a recipe for tragedy, a.k.a. Flowers of Evil. All tragedy fans must read this.
Dealing With Incest
If you can stand incest, that is. But before you immediately say "oh, incest is sickening, there's no way I can read this," let me tell you that the characters do not try to defend incest, but instead are pulled into this moral battle within themselves (especially the brother-the sister, I think, is less bothered by it. But then again, she seems to be less bothered by everything). The way they deal with their feelings for each other is very believable, and the mangaka certainly is not saying incest is a good thing. If anything, this story says just the opposite.
The Characters
The characters are all really interesting and believable.
Seh-Wa:
The slightly off-kilter sister. She's interesting to try to figure out. At first I found her to be annoying, but as the manga progressed I began to like her and understand her more and more.
Seh-Joon:
Seh-Wa's seemingly normal twin brother. He is a very likeable character, and you feel bad for him and how he has to deal with his sister's feelings. But as the series progresses, you also come to understand him more, and you realize he is much less two-dimensional than you originally thought. He undergoes some great character development.
The Supporting Characters:
Seh-Joon's girlfriend is one of the supporting characters. She is pretty much the same person the whole time, but she's not evil. She's just not as interesting. Also supporting, is the twins' childhood friend who becomes good friends with Seh-Wa. He has his own motivations and interesting past that play a part in this story, and he ends up being a lot more important to the plot than you originally thought.
The Plot
Another great aspect of this manga is that about half-way through, the plot seems to flip over and you find yourself forced to re-evaluate the entire situation. Once I got through the first several chapters (which were a little predictable), this story kept surprising me, and my opinions of the characters kept changing. Once you've started this manga, you will be compelled to keep reading.
The Ending
Also, when reading this, keep in mind how the very first chapter begins because it all ties back to that in the end (which I think is just beautiful storytelling).
Even without that, though, the end of the story was simply perfect. It could not have been better for this manga.
In Conclusion
So the storyline becomes interesting, there's some great character development, and of course the art is just beautiful. If you like tragedies, and can stomach incest, you must read this. If you can't, then avoid this story like the plague. Because if you read it, it will haunt you . . .