This would be a great Metroid game, if there were any Metroids...
Metroid games always had something to do with a metroid, this one you find a total of maybe 6.
The light and dark world was very random if they would have just named it "Metroid Prime Echoes" It wouldn't be so random. It also really has nothing to do with the first Metroid Prime, which makes the sequel worse.
Graphics are wonderful, however the replay is not, they give you a hard mode but it's really no fun, there isn't any motivation of playing hard mode also. The two-player feature they added was quite boring, it could have been better.
Despite the fact of the lack of Metroid's and the replay this game is really excellent controls are easy the puzzles aren't really that hard, so overall this game isn't half bad.