I read the 3 books brilliant. I have watched the Swedish version of the first book with subtitles and think this film version was better than the version starring Daniel Craig. if I had watched the English version first without reading the book then I would not have been able to follow the story. the books are better than both film versions
I wouldn't touch the books with a barge pole after watching the film, especially the sequels, which are horrific. If you've watched the hollywood version, i would suggested watching the Swedish films as opposed to reading the books. The next two films aren't that great either, but that's because the books are dire.
The first film was pretty good, as it essentially wipes out all of the non-essential drivel ( and there's a lot of it ) and keeps the plot moving forward. The next two books, however, had about ten pages worth of real plot, the rest filled with mangled sub-plots and filler. And that will most likely show in the Hollywood sequels much like it does in the Swedish versions.