We're aware from the moment Burt addresses Leonard by his first name - after Leonard has introduced himself as if they've never met before - that something's wrong with this situation. That makes us interested in their relationship - and in order to work out what that relationship is, we pay attention to the exposition. So we have an immediate use for the information - it explains what's going on between these two people we're interested in. It's also useful having a character who can't remember what he's told people before and can therefore repeat himself with impunity! (Though in fairness, I don't remember that being overused in the film...)

Reinforced, cut-to-the-quick information. Detection and discovery, this dialogue makes the audience work double-time to keep up with Leonard's view of the present and Burt's knowledge of the past. One has to stitch the different viewpoints together to see the whole pattern. Dialogue that makes you work to keep up: challenging and entertaining. What can be better?

I love what both of you said, Debbie and Mike. Wow. Bang on.

When you have bad exposition, you've got two people having a conversation that is very unnatural and awkward because people don't generally sit around telling each other what they already know. The dialog exists only for the audience, not for the story. In Leonard's case, it's completely believable that he's delivered that speech a thousand times; because of his condition he HAS to go around explaining himself. So the character isn't saying something just to spoon-feed the audience; he's saying it because the action forces him to. He HAS to explain himself to Burt regardless of whether the audience is watching or not. Because it's so natural, it doesn't clunk on the eardrum, and because it's so weird and fascinating and necessary (we're already confused that we're seeing things out of order), we eat it up.

My favorite bit is: BURT That must suck. All… backwards. Pretty much sums up the whole movie while managing to feel right in the scene, further Burt's character, and define Leonard's journey as both the end for him and the beginning for us.

Fantastic analysis, everyone! I am so impressed, I just Tweeted the world with a link to these comments. I'd just add that the dialogue uses at three of the principles I like to talk about in terms of exposition: * Mystery: Learning about the Leonard's condition. * Revelation: Burt has heard all this before. * Fascination: As Saint excerpted, "That must suck. All... backwards." Compelling to think of living like that. Great work. *