I don't know... people who liked Infernal Affairs weren't too fond of The Departed remake. I haven't seen Internal Affairs, but it is apparently full of nail biting suspense.
While I really enjoyed The Departed for what it was, I don't think it deserved as much praise as it got. I really enjoy Martin Scorsese movies, especially stuff like Taxi Driver and Goodfellas, but he really can't create suspense -- though who is to say he is trying. He is fantastic at creating atmospheres and capturing the authenticity of the locations he is shooting for. He is also easily the best at getting the exceptional performances out of his actors, and shows amazing attention to detail in just about every shot.
The thing about Martin Scorsese movies is that his signature is so obvious that I can't ever fully immerse myself in his pictures. I never feel like I am watching real people, but rather am reminded at every other scene that it is a Scorsese movie. It isn't his fault obviously, it is just that some scenes are shot so beautifully that you are reminded it isn't real.
There are plenty of murders in the movie, and there is always something funny or serene about the way they are presented. I think that's one of the reasons why his movies lack suspense.
Even the excellent score for the movie was typically poetic and complimented the movie well, but was counter productive in terms of suspense.
What I loved about The Departed was the hilariously dark sense of humor, some great performances, excellent cinematography, and well woven plot details. While I enjoyed Jack Nicholsan's performance, he wasn't brilliant or anything... he was just being Jack. I honestly don't hold JN in high regard, because he pulls out the same schtick in every flick.
I did notice a few editing problems with The Departed, and transitions between scenes were uneven at times.
Overall I'd put this behind Goodfellas, Taxi Driver and The Aviator, while it was far better than the horrible Gangs of NY.
I don't think it deserved the Oscar for best picture, but probably picked it up as a recognition of his career. But that's pretty typical of the Academy.