Really liked the fact that unlike a lot of serial killer movies it focused less on the murders and more on the actual investigation. However, it's still quite shocking in places and there's a few tense moments too. It does drag a tiny bit at the end, but I think the interesting story, direction and attention to detail make up for it. Downey Jr., Gyllenhaal & Ruffalo all give great performances; you get just as excited then frustrated as the characters with the endless clues and also the miles of red tape involved in the investigation. Overall, a good detective story.