The film version of The Prestige actually pulls something off that's very rare; it ended up being, in many ways, an improvement over the original book. Frankly, the Nolan brothers have taken a lot of liberties with the original story, leaving a lot of key elements from the novel out. Which, considering the often times confusing aspects of the book, can be considered a good thing. To a certain point.
The basic storyline remains intact: two rival magicians from the 19th century play an escalating game of one-upsmanship that has very tragic and frightening results. What the Nolan brothers actually improved on, was the heart of the story; the relationship between these two terribly obsessive men. The film fleshes out the lives of these characters, in a way that was lacking in the book by Christopher Preist. Both Bale and Jackman are excellent in their roles, as is Michael Cane. Scarlet Johansen is more less just eye candy for the last half of the film, and she tends to blend in with the scenery.
I do have a few complaints however. In the book, there is a fascinating back story involving the children of the two magicians meeting years later, which has been completely left out, and the final scene in the novel is far more unsettling and actually darker then what made it onto the screen. The actual 'surprise' ending of the movie, lacks the punch and truly creepy feel of the last few pages of the book. But having said all that, the film works on so many levels, that i can forgive the changes that were made. At the end of the film, you do indeed want to watch it again, which is always a sign of a great movie.