I have mixed feelings about this movie. I feel that it could have been a really good movie but the screenplay is very sloppy because the plot has no plausibility. A cloning and teleportation machine around the start of the 20th century?! Sure, Tesla did propose some crazy inventions in his lifetime, but none of them were actually invented.
Anyways, I think the idea of Borden having a twin was brilliant. The foreshadowing was very well-done and consistent. All that they needed to do was to come up with some PLAUSIBLE trick that could have enabled Angier to do the Transported Man. Then the movie would have been sound. (Well, there are other inaccuracies, such as the fact that IIRC the magicians wore the same disguise every time, but I won't get into that.) The movie reminds me of the Inside Man, except for the fact that the plot is not at all sound.
I think the directing and the acting was great. The non-linear plot really worked IMO. The rivalry between the magicians and the characterization of the two men and their loved ones were really well done.
What I don't like is the plot hinges on glaring inaccuracies. Such as magic. I mean the cloning machine and the teleportation and all those absurdities. You can't do that in this kind of movie. You can do that in Pan's Labyrinth, but not in this kind of movie. In Pan's Labyrinth there's a tacit agreement at the very start between the viewer and the director that magic is a-okay. But not in this movie.
Furthermore, I think the portrayal of Tesla was only mediocre. They made him into a symbol, not the man himself.
Summary: Compelling, but a disappointment. Lots of potential, but not enough follow-through. Sloppy.