Abyss was absolutely beautiful and well integrated in my opinion. I hated the implications of beauty the whole thing had. But otherwise the crime, supernatural activity and romance was well integrated. I understand the criticism that there wasn't much explanation about the abyss itself. But IMO since it was just bestowed on Cha Min, they are themselves slowly discovering things about the marble. It was understandable to me that the story ended without too much being revealed about it as it was unnecessary and did not contribute to the story as a whole. I loved the crime aspect of it. The second villain did not have good enough motivations in my opinion. But the first villain was iconic and well written. The series kept my interest high and kept me on the tip of my feet. I wouldn't recommend it to most people. If it seems to be your type from this, then go for it.