Location: You're pretty good.
Well I've said that in other threads. The movie treats the audience pretty much like its story treats the normal audience that's in the story (the people paying for tickets to see the magician's performances) and Angier. You're pretty much Angier while you're watching the movie. Prestige is a continuation of Memento's finale logic. People lie to themselves to be either happy or to have a reason to go on, because they're unable to let go and get over it and they don't know what to do with themselves if there is no drama and tragedy that would drive them forwards. Angier was a bit like Lenny in that sense. Without the condition though. In other words Lenny was letting himself be blinded using his short term memory loss as a tool to fool himself. Angier was fooling himself out of anger and hatred. He needed a reason. An emotional motive upon which he could thrive. God knows if he would've made it as a magician if it wasn't for that particular revenge motive.
That said: you, Viewer, yes, you, sitting there, reading my diary... are willing to be fooled. So you could go on. So you could go on watching the trick and get a kick out of it. So you could go on with your happy life. So you could go on watching the movie while constantly denying that the twist at the end could be so obvious. You won't allow yourself to admit that it hasn't been disguised enough for a reason. There were a lot of details that told the secret and they weren't just 'foreshadowing'. The subtlety of the trick makes it invisible for some actually.
The audience of this movie consists of three parts. There are the ones that didn't notice the details and were surprised by the end. They thought the movie ended there and there wasn't anything more to it. Then there are those who were dissapointed by how obvious it was. They knew Borden and Fallon were twins and thought that it was cheap to leave it so. The third part is that part of the audience that, after being fooled, after assuming that 'this can't be it, it can't be so obvious' (pretty much like Angier denied that Borden's using a bloody DOUBLE), realized that it's all part of the trick and that they're supposed to be linked to Angier and the blind audience. Pretty much like bluffing in poker.