Two me, it doesn't really get good until the first two chapters are over. With that being said, in my vision, you'd have to be patient to get to the good part. I think the first two chapters don't have solid bases and seem like any other S/M/yakuza manga. Sensei doesn't seem to have any personality at first, and Takagi's another common yakuza-boss-seme: violent, cruel, but mostly spoiled and childish to the point he does whatever he wants because he has power.
Then the manga suddenly turns into something else entirely. The story gets twisted.
Takagi turns into the star of the manga as his personality changes completely. He then becomes a puppy, whose love towards sensei is so big, he's damaged by it. He becomes clingy to sensei and waits for praising to even stand up on his own. More than that, he actually becomes weak and desperate, completely lovesick. To that point you must understand how it is to feel bad for a character, because his side is really sad.
Sensei, on the other hand, I started to hate. He is the one who was responsible for Takagi's personality change and yet he was all condescending, saying "he bores me" and sh*t. And he gets even worse, looking only for pleasure and disregarding Takagi's feelings towards him, with whoever makes themselves presentable for his needs.
The ending was, to me, about one of the only things that actually made sense. They didn't really end up together? No, they didn't. But sensei declared, in his twisted way, how special Takagi was for him. The dream shown at the end is very subtle, so I understand why a lot of people were dissatisfied. To me, it means they found each other in their little corner of the world, even if nobody else was there.
As for the art, it isn't very good, and frankly, the 5th boss was too ugly to be in yaoi. The good think about it were the sex scenes: not enjoyable in the least. I'm not those kind of people who are totally against rape in yaoi, but since they were indeed rape scenes, they were horrible and I didn't like that. And that's exactly how it's supposed to be, so I consider that to be good.
Well, as opposed to everyone else, I'd rate the first two chapters very low and the last two high, so I'd give a medium rate like everybody else, but for different reasons - more like opposite?
PS: Doubt: Goto almost seems to be in love with Takagi, or is it just me?