I loved this game, had lots of fun with it. The relationship system however was "weird", I either missed the tutorial or it just sucks, but I really feel like I missed something there. It is, however, a truly minor aspect of the game. The main mission is pretty serious, although it strongly carries a kung-fu movie undertone, after all, even though you can go around as armed as any GTA character you'll probably be doing most of the combat in hand-to-hand combat, which is a kung-fu spectacle as expected
Driving around is weird at first because you actually have to drive on the left, but it's fun. There's also a "hijacking" system for you to jump from one car/bike to another, something that goes totally against the laws of physics, but it's so damn fun you won't really care lol
Pretty great graphically speaking with good gameplay, and it's undeniable the way it looks like Hong Kong. It's not as big as GTA, but it's big enough to grant you fun worth your money.
I heard it say this was supposed to be a True Crime title, they changed the name because there were a lot of complications during the production of True Crime, so much so they feared it would actually harm the game's performance in terms of sales and all. So they simply called it "Sleeping Dogs"; between you and me, I believe this story because it DOES feel like a True Crime game, only better.
In case you don't know, you'll take the role of an american cop, natural born in Hong Kong, who goes back to his birthplace to infiltrate the Triad... Or something like that, I'm not so sure anymore, been a while since I finished it. If you want a shorter version of the story watch a great movie called State of Glory, only you have the Irish instead of the Chinese, and you get Gary Oldman doing crazy shit, because that's what he does best lol