It was boring, slow, the "mystery" was never really developed and the solution was a total letdown, I figured out the "twist" in about two seconds, the two protaginists' plotlines (before they teamed up) were so different I felt like I was watching two different movies, it had serious ending fatigue, and the female protagonist was a total Mary-Sue (although I didn't mind so much in this case because the movie was otherwise so dull that her antics at least entertained me a bit).

Don't really see why everyone loved it so much, but whatever