I'm a couple of weeks late in doing this post, so we'll see whether the book is still fresh enough in my mind to give some good thoughts on it.
First off, I enjoyed this second installment in the Millennium trilogy better than the first one. It's more of a thriller than a mystery. I thought it was a better story overall with fewer plot points that didn't really go anywhere. Stieg Larsson does an excellent job of fleshing out the character of Lisbeth Salander and expertly ties her dark past into her current predicament. The gist of the book: Lisbeth is charged with a triple murder, and she and journalist Mikael Blomkvist work (mostly separately) to clear her name.
Of course no book is perfect. The structure is strangely done. The first section is written almost entirely from Lisbeth's point of view and concerns events on a Caribbean island that have no bearing whatsoever on the rest of the plot. Once Lisbeth is accused of murder, she disappears from the narrative entirely for several chapters, while Blomkvist and a team of police inspectors take up the storyline. An odd choice, in my opinion. On the other hand, I do like how even when Lisbeth returns to the story, Larsson withholds for several more chapters whether she is guilty or not.
I'll probably get around to reading the final book in the trilogy later this year. For now, I'm finishing a biography about Annie Oakley, and then plan to tackle a writing-related book by Donald Maass: "The Fire in Fiction."