Much, much better than the first two in my opinion. Less action might not be to everyone's taste, but I found that it read like an elaborate chessgame where different players made moves that affected the entire book and the actions of others. I also really enjoyed reading about the inner workings of the Swedish government (however true it may be). It was a really well thought out consipiracy theory plot, which, thinking about it, may make a reread of the second book, The Girl Who Played With Fire, more enjoyable than the first time I read it.
The book had a lot of new additions, but I have to say I liked the majority of new characters. I found myself rooting for every little victory against The Section and genuinely concerned when any of them were in danger. Lisbeth, who I have to admit I was not too fond of in general, I really enjoyed in this book. Partly because she gets less screen time, but also, she's at her best solving cybercrime and communicating via computers and word documents.
Notably, I enjoyed the courtroom scene at the end of the book that finally acquits Lisbeth of her 'mentally unstable' status. Arguments presented by Advokat Gianini were concise and powerfully given and it was nice to see the looming and tiresome Dr. Teleborian figure taken down a notch.
As the others though, the book could have used a bit of editing. The Erika Berger stalker plotline felt out of place in the book--it was almost like the author threw it in randomly to comment on harassment of women in the workplace, but I felt the ignored-schoolmate plot has been overdone and it never really tied in with the rest of the plot. Also, Mikael's 'romance', if you call them that felt flat and unnecessary. Yes, we know he's attractive to women, but he's really at his worst when in a psuedo-romantic relationship. Friends with benefits is probably the state that suits him best.
I would've also liked to know what Lisbeth was planning to do with her 2.4bn kronor, but I guess with rumors of a half-completed 4th book, maybe I will find out! A nice sequel and ending to a very interesting plot.