A day or two ago I had finally finished the first book of that hyped Larsson's trilogy.
It maybe explains something about modern culture, when in the same story the negativity of some filthy character is emphasized (in addition to other facts) with a scene of him having sex with an underage girl - and only a page or two later, appearance of the positive character is described by mentioning among other epithets her "childlike breasts".
I was rather thrilled with the plot on the middle of the story, but the outcome was weak. Also, almost all the characters are flat and hence, predictable. Especially Salander is nothing more than a stereotype fair of a "vigilante girl" type: black leather, tattoos, tough childhood, autistic-but-talented (and talented in hacking computers, of course) etc.
Still, this book makes great introduction into Swedish way of life, laws and customs (well, at least for a person like me who had never been to Scandinavia). Summarizing: not a must, but probably you won't regret.