An exceptional novel that I almost gave up on in the beginning. As bad as the first 1/4 or 1/3 was, the book picks up speed and quality after the death of a noted computer specialist--and the emergence of Lisbeth Salander. Whether by design or by accident, the book becomes extremely good after she emerges. Her character meshes everything and everyone else, and makes it all work. Before she appears, it all flounders.
The four books have the same tagline on the front cover: "A Lisbeth Salander novel." Though Mikael Blomkvist is also in all four books, Salander, again, is the fulcrum that powers the works. David Lagercrantz, taking over for Stieg Larsson, undoubtedly knows this. But you wouldn't know that at first, as Lisbeth is behind the curtain and is only barely even spoken of. Larsson notoriously hindered his last novel by doing the same to her--keeping Lisbeth prone in a hospital obviously paralyzed her movements, and when Lisbeth isn't moving, neither is the book she's in.
And so I have to believe that it is by design that she doesn't appear for awhile here. Maybe Lagercrantz believed he was building tension, or maybe he believed he didn't have an open door for her until he finally did. I don't know, but these books don't work like Dracula did; the more you didn't see the Count in the book, the more mysterious and terrifying he became. Salander isn't like that. She's not terrifying (except maybe to the men who hate women); she's kinetic. She bristles with energy and fury. (Maybe her fury gives her this hyperactivity and kinetic energy.) It's possible that Lagercrantz believed he could offer up too much of a good thing by making her appear too early. If so, he's probably right, as it's really not possible that someone of her limited physicality could actually brim with as much energy and survive the shocks her flesh was heir to. (I'm a rather hyperactive slim guy, but I haven't been shot multiple times, or been abused as she had been in her youth and in the first book.)
The writing is very Nordic Noir: very dry, very "Just the facts, ma'am," and very specific. In the beginning, this was to the point of being pedantic, and it almost became stale before Lisbeth appeared. Then, the writing fit her persona, and it all took off. Lagercrantz also does a good job playing the cards he's been dealt by the first three books, and then running with them. Though his writing is a little different from Stieg Larsson's, by the end it does seem possible that Larsson could have written this. None of the characters do anything they shouldn't do. They don't behave strangely or do strange things. There is a relationship that gets downplayed here, but I was expecting that. For this series to take off with Larsson's passing, one relationship had to sort of cool, and one had to sort of subtly pick up. If you've read all the books, you should be expecting it, too.
And, finally, Lagercrantz somehow manages to flesh out Salander here, without going too far. He does toe the line, but he doesn't cross it, and what we learn and see of her past is worthwhile, riveting, and completely at home with her character. There are also some very interesting premises here, including a neat little section that shows how computer intelligence has increased in just five years. This section posits the question: What would happen when a computer can learn by itself, and fix its own mistakes? A character wonders what a computer would think when it realized it's owner--who can turn it off, remove its insides, and essentially kill it--is much less intelligent than it is. It all sounded too uncomfortably like a computer very soon could be some sort of HAL, Skynet, Blade Runner hybrid. This stuff alone made the book interesting and worthwhile to read. It all stays just on the good side of info-dump. As in Larsson's books--and as in the genre itself--there is a lot of character-explaining here, and they sometimes talk a little too long, longer than it seems that real people do. But, again, it stays just on the good side, and it never slows down the pace of the book once the pace establishes itself.
And so finally this book was a winner for me. It's clearly better than the third Larsson book, possibly better than the second, and equal to the first. Possibly it's better than any of them. You should read it.
P.S.--Unlike most book series, this book builds upon and needs the other three, and so the reader should read each of those before he reads this.