The script is terribly naive and straightforward, and that is the only thing that spoils the movie. The scriptwriters' shallow knowledge of geology, physics and just logic makes it too fantastic and shallow, and that's a pity, because this is the main drawback, and without it the movie would have been just great. More realism and logic would have benefited it. Let it be fantasy, but still there is a claim not just for fantasy, but for science fiction! And this is a rarity in movies.
Liked the cast: Hilary Swank looks very colorful, and dilutes the male cast very harmoniously. Tucci is terrific in the role, he really admires his performance in almost every movie. I will not describe the merits of each individually, but still say that they have created a 'team' worthy and believable. It is all together they made this film at least interesting.