Played the game for three hours and here is what i think.
Let me start off with the game play,there is nothing new about it. what you find in any other open world game like saints,mafia,batman AC,the same you will find here as well.but what makes it intresting is the way have been implemented,everything is very streamlined and has been designed in a way that it makes you feel like you are playing an Honk kong action movie, fans of johnny to, and john woo movies will feel right at home.the game also as a levelling system which is very stream lined it wont be like the ones you see in your typical Action RPG,atleast it wont be like how it was in dark siders 2.the fighting mechanics has bee lifted stright from batman AC with a minor change which is using your environment as your weapon,you can kill your enemies in so many diffrent ways that it is grotesque as well as very entertaining.when it comes to driving,all your real world physics has been chucked out of the window in favor for unrealistic,easy to drift driving mechanic.again the way this game plays will make you feel like your watching an HK action movie.you also get your standard fetch missions,camera hacking mini games,dating just like GTA 4.there is an online feature in the game called social hub where you get to compare stats with your friends or even challenge them in certain areas like racing.
Now onto the graphics,The world of Sleeping dogs has been crafted in such a way that you get to know what it feels to be in HK without actually being there,all the NPC's look believable,the neon lights hanging around the city to the smoke field kitchen rooms and the elders playing mahjong in every nook and corner of the back alleys everything has been put there inorder for you to get the Honkong feel.there maybe some complaints about the character models being bad and the characters dont emote well,so far from what i have seen what they have done with characters seems just enough and makes the story believable.
As for the story,i cant really comment on that as i havent completed it yet but so far it has been good really good.
Overall the game is GREAT ,its fun to play and thats the only thing matters.
PLayed it on the PC btw