This serial killer crime movie has some beautiful pictures with snowy Norwegian landscapes. It also has a fine cast with Michael Fassbender, Charlotte Gainsbourg and even a plastic version of what used to be Val Kilmer. What it doesn't have is a good plot, and many scenes only feel randomly connected or even disconnected, and many scenes have close to nothing to do with the main story.
I can't say if it's the book, or the script, or the direction that went wrong. But the book is generally said to be very good, and the director Tomas Alfredson was behind the vampire masterpiece "Låt den rätte komma in (Let The Right One In)" , which was actually better than the book it was based upon. So I'll make a guess and say that the script must have sucked. The cast can't do much to save the movie with a script this bad. There's a bit of gore and blood but not nearly enough to save it either.
It's not a boring movie, it's just never really exciting, and that makes it rather pointless and disappointing.