The story of this trilogy is a peculiar one — Larsson meant for the series to be longer — something like 10 books — but he died of a heart attack in 2004, after completing only the first 3 and parts of the 4th (in Swedish). He was quite an activist in Sweden, and there are personal influences pretty clearly in his characters.
I liked the first book a lot — it was really a locked room mystery — very fun. The second book centered more on a type of espionage. The third book, which isn’t yet published in the US (but is in the UK, which is where my edition came from), wraps up a lot of loose ends, but I found it a little bit boring. Lots of basic police work, lots of courtroom dialog. Satisfying as a way to wrap things up, but not as intense as the first book or as wide open as the second.