I have recently purchased both the UK edtions and the American editions.
The book is one of those 'un-put-downables" as a read. What makes it special is that it is part of a series called "The Millenium Trilogy" which has become an international sensation. What is unique is that the author died before any of his books were actually published.
The first printing in the UK was very low. I believe it was less than 3,000. American firsts have seen a spike in value as well.
This is one of those ideal books to collect: a fantastic story and a highly sought collectible.