Well, I gave it a 10, and I don't give 10 easily - out of 236 dramas I've watched I gave 10 only to 10 dramas so far and KP is one of them. The reason: I think that this drama is important for BL drama industry and it will have a huge impact on the future productions. Why? I want to point just a bunch of reasons. (The review might have a slight of spoilers for character development)

1. ML is a bad guy and it's working.
We all have seen this kind of plot - bad ML meets a nice ML, they fell in love, then BG stops being bad guy, turning good and his bad deals are forgiven, at the end of the day he is a good person thanks to the good ML... Not here! Lets turn the table - Kinn is a bad guy, a killer, a mafia and he turns our innocent, poor Porsche into a true evil badass that kills without a second thought. What good guys? They are all bad everywhere and we love them, we have to or just drop the drama. This is their life. Kinn can't escape from his evil life. He needs to keep going and since Porsche can't leave him, he decides to give him this bit of a normal life and still accepts his bad side, protects him and supports him along the way.

2. Not healthy relationship but it's working.
I mean Vegas/Pete of course. This relationship, the development of their characters was very hard to portrait, to do it right and at the same time to convince the watchers that sort of relationship is okay, you can watch it. I'm sad that VP didn't get more time screen but the production used their time very good to show us the deep emotions of our leads. Vegas is a very complicated, deep character with huge scars and even trauma. How to turn such a psycho into a lovable lead? Well, he wasn't really lovable... but he made our hearts broke so many times. Oh Vegas... please remember to feed Pete well.

3. Taboos aren't taboos anymore.
Drama isn't scared of hard topics - murders, mafia deals, tortures... Usually when we get mafia drama such topics are either avoided, or our mafia lead turns to be an okay guy and he doesn't use violence or do bad stuff like drugs, kills, etc. KP isn't afraid of shwoing us these things. Thank you, for giving us a mafia which is a mafia through their actions, and not only by their names.

4. Chemistry overload - this is what the desire looks like.
Our MLs love each other very much and we can really see the devotion in their eyes. All the actors did a great job here, they love their roles and put a lot heart into their play.

5. Predictable? Eh, nope.
When you watched many dramas, you can easily predict what is going to happen in episode 3, 6 and 11, right? It's so predictable. Not here! Each time (or rather most of the time) I felt like I knew what would happen it would surprise me and it always gave me nice surprises! The pacing isn't predictable.

6. High production quality - you shouldn't do it so perfectly, 'cause you just killed other dramas.
The music, the color scheme - these artist in the team were amazing! Dude, their know how to do their job and they do it the best! They know what kind of music, what colors and composition use, and how the camera should work during this scene and that scene to make the viewer feels that right emotion and nothing else. This production is so much on a different level.

THIS is how you do the drama! And now that we know that you can do this right, we want more dramas on this higher quality level. I hope that people will watch this drama and learn how to do it. Just do it right. Stop producing predictable crap with no character development and low overall quality. You see, there we got Kinnporsche - a drama about a mafia falling for a regular sweet guy - such a cliche, naive romance, right? And here this fanfic-like-plot turned into a deep masterpiece. Thank you, guys, for showing us that this is possible! I loved it.