The artwork alone blows me away. It's as beautiful as the cover, and does almost a watercolor like shading that looks so nice and accentuates the gorgeous, realistic character designs and linework. Great attention to detail, character development, story.
One warning, though. The subject matter necessitates the portrayal of some violence and it can be a little rough getting through it. (Think knives.) I'm someone who is bothered by themes of torture, but this wasn't exactly in that vein and it wasn't so horrible I couldn't make it through. (Goth, on the other hand, did bother me. M.P.D. Psycho as well, but I found it to be more readable and somehow less disturbing than Goth.) It's more like... what violence is in there is just enough to remind you that the serial killer guy is not someone who is simply misunderstood. There is some seriously messed up things with the way his mind works, and the way the manga is written SHOWS you that.
Of course, the psychiatrist character is compelling to look at, and you want to root for some yaoi, but at the same time, you get reminded as to how that might not work out so well for him if it is with the crazycakes criminal guy (also attractively drawn, though they impressively make him look quite unhinged).
Finally, I want to impress upon anyone reading this, that THE WRITING IS REALLY GOOD. Not only is it written with intelligence, creativity, suspense, and great pacing, but you can tell it DIDN'T suffer in the translation. It is well worded in English and had proofreading to boot. The beginning of the manga is actually just prose, and if I could find books like this, novels, I would buy them in a heartbeat.
My only... gripe? might be that the sequence directly after the prose is disorienting and too sudden in my opinion. It is the only misplaced feeling thing. Everything after that is gold.
BUY IT. (Just beware if you are super squeamish)