This book has a few flaws. The male lead Mikael Blomkvist is a journalist/magazine editor just like the author! Unsurprisingly, the author describes in deep detail what Blomkvist enjoys about his job, reminding the reader why you don't want that job. The author also considered himself a tech expert, and describes every piece of computer equipment ad nauseam.
Howver, those flaws only stand out because the book is amazing. A great story with intense characters (although I look forward to more backstory in the sequels) that draws the reader along without resorting to Dan Brown-style gimmicks. There are some very disturbing scenes (I don't want to see the movie, although it's supposed to be excellent, because of a few of these), but they're never superfluous. I can't recommend it enough, and I'm looking forward to reading the sequels.
Forgot one thing when I first wrote this review: the translation impresses me even more than the writing. Reg Keeland took a well-written Swedish book, and produced an at-least-as-well-written English version, which is amazing.