I recently saw the third installment in this trilogy (The Girl Who Kicked the Hornets' Nest) and was a bit disappointed with it.
The first (The Girl with the Dragon Tattoo) introduced us to a character (Lisbeth Salander) and a Swedish world that we had not seen before on film. This made it interesting.
Her story continued in the second part (The Girl Who Played with Fire) and this gave us a bit more background on her particular life story.
But this last part seemed only to justify the completion of the trilogy and didn't really add much as a film experience.
Based on the über-popular novels by the late Stieg Larsson, these Swedish films are set to be remade very soon in Hollywood.
I have not read the books but I can assume that the old adage holds true that the book was better than the movie...