This is what I call a great action game. You have got the whole town of Hong Kong right at your feet. You can do basically almost everything there: you buy food, you buy clothes and you can upgrade your melee moves and your cop side of your personage. You are an undercover agent, who must clear the streets of the triads.
You can perform combos which can be upgraded. The town of Honk Kong is wonderfully designed and the streets are full of life. You can drive almost any car, you can hijack any means of transport.
The story is pretty interesting and I won't spoil it for you.