I re-watched it twice recently after seeing it once a few years ago and it has sailed up as probably my favorite Nolan film, which had been and still kinda is (but in another way) TDK. But I discovered now that Memento is so much more than just it's twist and unique storytelling (even though it's brilliant). And the first times you see it you use your brain so much you forget your feelings. It is a super-smart film and the way it is constructed is fantastic but it is also an emotionally rewarding film with alot of great and quotable dialogue and/or individual lines. First time you see it, it blows your mind. But it gets even more rewarding upon repeated viewings.
Guy Pierce is just fantastic. An understated performance. He makes it with small- gestures, mimics and phrasings. A beautiful performance.
Editing is great and visually it's stunning. Love the light colors combined with the film noir feeling of the story, great contrast. Also love the repeated use and/or combo of light brown and light blue. Gives the movie a special feel, a floating feeling which adds to the no sense of time theme.
Music is sparse but hugely effective when used. As in the brilliant opening scene,quickly setting the mode. In the scene where Lenny wonders how he can ever heal (maybe my favorite scene, it's beautiful) and of course the ending.