Yes, I played Sleeping Dogs, and loved it. It's an awesome game, if you like open world and story based games. I thought the story was great, and the ambience and atmosphere were superb, especially the depiction of the city of Hong Kong, just amazing. I have never been there, but the game makes it seem like the city it comes to life, and you really get a sense of the pulse of and flavor of this place.
The other reason I loved it is that it was made with influences from those Hong Kong action movies, that type of genre, such as the classic movies John Woo made, such as "The Killer", and "Hard Boiled". You play a character who is an undercover agent who is infiltrating a very dangerous mob and mafia-like gang, and the story has classic crime movie twists in it. If you liked any of those movies or in general, crime stories, then this game is one to get.
I never played any of the Mafia games, but was excited about Mafia 3, but I have read that it has a ton of problems (bugs) right now...maybe when it gets patched up in the future, I will give it another look.