I missed Memento when it was first released but I wanted to see it now as it’s been claimed that this film offers one of the best depictions of anterograde amnesia (inability to form new memories).
I thought it was a very good film. It is shown backwards with the start of each scene continuing where respective subsequent scenes finish. The effect of this is to put the viewer inside the head of the amnesiac protagonist. However this does mean confusion for the viewer which lessens as you progress through the film. Don’t be surprised if you need at least a second viewing to get a complete understanding of the movie. On my DVD there is an option to view the film in chronological order.
[SPOILER from this point on..] Even after seeing the film in chronological order I still found some ambiguity regarding the Sammy Jankis story. My understanding is that this character exists only in Leonard’s imagination. If Jankis did exist in the past there would be no need for this to be tattooed. Sammy Jankis is an imaginary surrogate for Leonard’s own experience, as told by Teddy in the final scene, who I assume is not lying at this point. However in this scenario Leonard has forgotten that his wife was a diabetic, which implies that he is suffering from long term as well as short term memory loss. But if this film is supposed to be only about anterograde amnesia, I have some doubts whether this interpretation is correct.