The GameCube's Greatest Game
I won't go into a whole lot of detail (watch the video review on gamespot if you want detail) but this is a fantastic game. Graphics are some of the best on GameCube, addicting and fun gameplay, and with sequence breaking, terrific replay value.
One of the best parts of Metroid Prime is the atmosphere it creates. You will become absolutely immersed in this somewhat creepy world. With no loading times, great music and visuals, and a unique way of advancing the story (scan visor), AND the first person view makes you feel like you are Samus.
If you own a GameCube you need this game. It's that simple.