Apollo 13 is a masterpiece that manages to keep you in suspense despite probably knowing the outcome to the story already. It balances moods perfectly, breaking up tense scenes with lighthearted moments and humor, but never feels out of place or forced.
The cast is legendary, and they all do an amazing job of selling you on their motivations so every disagreement feels like two people having conflicting ideas of the best way to solve a problem, not an argument thrown in for the sake of drama.
This is a must-see for anyone, whether you're a film buff, a space-historian, both, or neither. You're going to enjoy it, I guarantee it.