I just finished reading The Reading Ape's wonderful response/analysis of Joan Acocella's recent New Yorker piece on the popularity of Stieg Larsson's Millennium trilogy*, and I really can't recommend the Ape's post enough. The Ape does a great job of pinpointing specific answers to Acocella's question of why Larsson's books are popular, ranging from characters (the oft-cited Lisbeth) to packaging (reasonably attractive in almost every edition I've encountered) to the genre (popular around the world). I wanted to touch on a few other points.
Firstly, I have to wonder at Acocella's approach. Props are given for Larsson's storytelling abilities, but not much more. Acocella is right to say that storytelling is not enough in carrying a book and making it "quality", but I wouldn't dismiss Larsson's writing so quickly. It's not splendidly beautiful, true, but the sometimes awkward bluntness has its charm, as though the grittiness is part of the story itself.
Acocella should not dismiss storytelling quite so quickly, either. Larsson's books, whether because of marketing or actually because of superior talent, don't comfortably fit in the crime/thriller category. Perhaps I say this because these are genres I typically don't read, but the Millennium books do a good job of telling a story and not making the reader feel dumber for it. Part of it, as the Ape points out, is the setting. Distance a book from your own existence and that can make it seem all the more interesting.
Then the most basic matter of all: the popularity issue. Acocella seems at times to dismiss the popularity because of a perceived sense of, for lack of a better term, crappiness. It's as though Acocella commits one of the greatest book-commenting crimes in existence: assuming something to be unequivocally bad just because you didn't like it. Therefore, the popularity is a mystery, when it's incredibly, incredibly obvious: people enjoy reading these books. I enjoy, on a very basic level, reading these books. Acocella seems so surprised that people like a book that fits into a popular genre, that's got a character most find to be pretty kick-[...] awesome, and that is definitely easy to read. "But it's a bad book!" Maybe, but other readers found it to be a lot of fun. And so: popular.
The article has a lot more to it than these points that the Ape focuses on. Acocella writes a lot about Larsson himself, mostly raising strange conspiracy theories about whether or not he could have written the books and commenting rather casually on his personal and political lives (but in a very limited, carefully selected manner). It's an interesting article, but rather unsatisfying. Read the Ape's take on it instead.
* It should be noted that I have read only the first two books in the series, and neither was read in the English translation. In the interest of keeping this blog spoiler free, please refrain from mentioning anything from the second two books. Thank you.