Let's get the geek joke out of the way: no, it's not a biography of American recreational mathematician Martin Gardner. (Though that could also be a good movie, especially if it focused on his debunking of psychics and other pseudo-scientific nonsense.)
Rachel Weisz's performance in this movie won her a Best Supporting Actress Oscar, and it's well earned. I still can't quite forgive her for some of that Mummy Returns silliness, but I don't suppose I'd pass up a co-starring role with Brendan Fraser, either. And she does some truly heartbreaking work in Gardener.
The movie has some flaws, but is beautifully lit and photographed. There are two scenes in particular, at the beginning of the film, where the lighting changes within a single shot to illuminate a different character or background. They're not typically "spectacular", but they are gorgeous in their own right. It only increases my desire to see City of God, an earlier film by the same director and cinematographer.
Favorite inside joke: the movie production company is named Potboiler Productions.