This game is one of the greatest I've ever played. It has high adrenaline action and deep exploration. Play this game.
It starts out with Samus's gunship entering planet Aether's atmosphere. Due to the excessive dimensional fluctuations, the ship is forced to land and cannot leave until it repairs itself.
Samus eventually is pulled into a war between Dark Aether's Ing and Light Aether's Luminoth. She acquires dark and light beam weapons, a radar visor, and many other cool gadgets on her adventure to bring the planet to peace.
The exploration in this game is marvelous. You actually feel as though you are on a strange alien planet, shooting Space Pirates. The game also has some intense boss battles that, instead of testing your adventuring skills, tests your coordination on skill.
Overall, the game's graphics and music are amazing. The replay value of this game is a little lacking, since once you beat it once, you only unlock a hard mode, which I've yet to try. It also has a multiplayer, but it's a basic, average 4-player multi battle. Not too much there, but it does help sell the overall package.
Metroid Prime 2 was not too difficult for me, but it could spell trouble for some. It is not an easy game. There were a few bosses I had trouble with and a few places I felt stuck in. All in all, the game was great and I highly recommend it. Most local stores still sell it, and cheap - only for $20.
Buy this game.