What makes a good magic trick? I like magic tricks. Even as a kid I knew they weren't real, but it didn't stop me from admiring the skill and the how-did-they-do-that moment right after the prestige, the final act of a magic trick. It's a kind of awe. But the success of a magic trick is based on the audience not understanding how what just happened, happened. Every magician knows this, which is why they're wary to reveal how a trick is done.
And that's the problem with The Prestige. The movie is about dueling magicians and is in itself a magic trick. There are twists, double-twists, surprise characters, we don't have all the pieces, or do we, no we don't, yes we do, another twist, and then the end happens -- and Christopher Nolan reveals how the whole narrative trick was constructed, step by step. It's as if a magician just did the most amazing trick you've ever seen and then spends the next ten minutes explaining how exactly he did it. It's disappointing, deflating. Instead of feeling wowed, we feel let down. We could talk about the other elements in the film, like the acting or directing or set design, but all these are subservient to the mystery, and in the end there is no mystery; had the ending been more ambiguous I would've rated this movie higher. I've seen every Nolan film, and this is the weakest by far.