Thriller are often predictable, bad guys shallow and heroes just stereotypes - but not in Stieg Larsson's trilogy. The main characters are difficult to like sometimes, hard to understand and thus so much more human than heroes found in other books. They are not heroes, they are failed or shallow persons who struggle when they get drawn into danger and intrigues of unexpected extent. Especially Salander is hard to like and even harder to forget when one suddenly realizes: She is so special, so unruly, so crazy -I like her more than many other heroes of today's literature.
The story is sometimes wilfully delayed by longer disgressions on hacking, math ... but that is great nontheless, because it opens new worlds and allows to understand the peculiarities and quirks of the characters even better.