It's been quite a long time since I read Girl With the Dragon Tattoo. I was initially not interested in reading the follow-ups because I had heard that Lisbeth gets a boob job within the first 20 pages or so (so, not giving much away there) and that seemed quite out of keeping for her character. After reading the entire book, I would still say it's a weakness of the plot-- Lisbeth, who cares next to nothing about how other people see her, in fact would rather everyone ignores her-- wants to make herself look "normal" by getting slightly larger breasts. It's an odd thing to place first and foremost.
Of course, after reading the whole book, we get a slightly better idea about why Lisbeth is so socially deficient and that getting implants could be a teeny reminder to us of how much she really is hurting inside, no matter what mask she puts on for the world. In the end, it amounts to not much of anything overall, although I'm guessing it may come back in the 3rd story.
What struck me most, and this is what I likely forgot from the first time around, is that these are not edited for length. There are arguments for both sides. If you give Larsson free rein, he will tell you the entire story. It is 100% certain that he will then repeat himself over and over and over, but you are going to see the whole picture from everyone's point of view. On the other side of the argument, I would find it hard to believe that you couldn't edit Larsson's manuscript to remove the repetition but still leave the full flavor of the plot. It does sound like a difficult editing job, though, especially after your author is dead and gone.
Regarding the story itself-- it is not quite as excellent as the first one, but it would be damn hard to top that. And it is close. I also had a laugh out loud moment during the denouement. And knowing Larsson was a huge science-fiction fan made me laugh even louder. I'd be interested if others had the same reaction.