Can someone tell me why this film is so great?

I'm one of those people who didn't like the movie when I first saw it, and have grown to love it over the (many!) years I've re-watched it. The script is tight and sharp, with dry humor. The characters are richly-drawn and the actors fill the roles with great commitment, talent, and connection to each other and the story.

Incidentally, I disagree about Victor Laszlo's character and about Henreid's playing of him: I see Laszlo as Rick's mirror image: two indrawn, dedicated souls living in a dangerous world filled with injustice; one has been banished, hurt, and thinks he has given up; the other has been banished, imprisoned, hounded, and cannot afford to give up. Victor re-awakens Rick's willingness to take action again; Rick's attachment to Ilsa reminds Victor of how dear she is to him. By the time of the airport scene, they recognize each other as brothers. There's a reason that it is these two men that Ilsa loves.

I feel that Victor is not one-dimensional; his motivation in Casablanca is very focused, and he has little time in the script to exhibit much range of emotion, but it's all there: one example is the very early understanding that something strong has linked Ilsa and Rick - in the very first scene with the three of them: watch his expression. He's off to the side, but he's already added 1+1, and he's struggling. Late in, he directs the knowledge at Rick (paraphrasing: "I know, for instance, that you are in love with a woman. It is a strange coincidence that we should be in love with the same woman."). And then he tells Rick that he wants his wife to be safe and that he is willing to let her go with Rick, because, as they both recognize: "he loves her that much."

And then, watch Henreid at almost the last moment we see him, at the airport, when he places the final decision in Ilsa's hands, asking if she's ready. Watch the body language. It's very subtle, the slight stiffening of the back as he braces himself for her possible rejection of him.

To me, it isn't that Henreid's acting isn't of the same quality as the rest, or that Victor is a cardboard character. I did think this during first watchings, but on each re-watch, when I paid attention to Victor, I saw more and more in the character, and how, gently and surely, Henreid was feeding him. Conrad Veidt said of Strasser that he knew "this man" very well. I think Henreid knew *his man* very well too, and knew how he had to infuse him - not in the stark dark colors of Rick Blaine, but in the firm, quiet colors of a man who has learned to survive with his principles intact.