I dont know whats the story bout GTA but in Sleeping Dogs, it's a story of an American police officer that went back to his home town in Hong Kong in order to help the police shut down the triads. so he had to infiltrate into the triads gain trust and at the same time work as undercover police. so yeah, player will be able to do missions for both triads and police. besides there are side missions like helping the community, car and races. since he's an undercover cops, HKPD regarded him as one of the triads member and that means police chasing happens too.
oh not to mention the cinematic is full of vulgar words and quite brutal for some people though I enjoy it. ah well, it's a story about triad what do you expect? so far I'm halfway to finish the game. too bad i dont have joypad to play this game or I would have played nonstop. ^^ my keyboard and mouse are not functioning very well which add more frustration everytime i die doing mission.
here's a trailer of the game