It's difficult to approach the book objectively because I had seen the film long before (I saw it in theaters in October 2006). Let me just say that the book is much concerned with the magic aspect than the relationship between Borden and Angier. Yes, the feud between the two men makes an appearance every few pages and is a central aspect to the novel, but it is given much less weight and significance than as seen in the film version. Also, as others on this thread have already mentioned, the timeline of the book overruns the timeline of the film. While the film strictly focuses on the lives of Borden and Angier from their beginnings in performance til their respective deaths, the book extends to generations beyond that.

Alright, I'm already boring myself. Let me just say that the film takes the most interesting part of the novel and makes it infinitely better. The rivalry between two budding magicians is a very interesting plotline that, I think, wasn't done justice in the novel. Throughout, Angier and Borden repeatedly admit (to themselves, or their loved ones in Angier's case) that the feud is infantile and completely absurd. In the film, neither really ever backs down--it's a constant descent into madness for the both of them. For me, The Prestige on film was truly a character study of two men utterly obsessed with one-upping each other. In the novel, the obsession is evident but not entirely believable or engaging because of the constant reminders that neither magician really wants anything to do with it. In the film, they are much more cutthroat. As the novel progresses, the author seems to become, instead, more interested in the dangers of "true" magic. The last section of the film had a real "Frankenstein" feeling to it that was concerned with real-world consequences of such "true" magic. In the film, Angier's final apparatus, courtesy of Tesla, seemed more a realized metaphor for how deep the rivalry between he and Angier had become. For me, I never really thought about the dangers of cloning because they never really presented themselves to me as I was watching; rather, I was more startled by the lengths a man (any man) would go to satiate his obsessive desires. Also, I simply think that the general plot is better suited for film. In the novel the two narratives are completely separated while in the film they are ingeniously intertwined. In the end, I much prefer the film, but I saw it before I read its source material, so you can take it with a grain of salt. And the climax in the novel did almost nothing for me, besides quickening my pulse for a bit with its ghost-story-like ending.