Super Mario Galaxy © I give this game 4 stars out of 5.

Super Mario Galaxy is a fun-filled single-player or co-op game.
The latest in the series, Mario finally enters space!
Galaxy, with a full plot and just the right amount of cutscenes, delivers the seventh generation Mario on a plate. There are over 40 main levels, and 80 bonus stars attainable. You begin as Mario in a tutorial world learning the controls. Soon after, you'll be filling his redesigned pocket with over a hundred stars!
The many unlockable worlds found by collecting enough "star bits" (free-floating currency) are filled with fun challenges, harder versions of main levels, and the Trial Galaxy, with three planets that are the ultimate copies of the three "special modes" in the game.
Completely breaking out of the 2-D plane, Mario surfs, floats, and launches into space with the return of many classic enemies and new ones. There are 5 special powerups that enable Mario to transform into a flying bee, a Boo, a fire-breathing pyrotechnic, a master of ice, and a secret found late in the game.
After Princess Peach's entire castle is lifted by Bowser (suspiciously remniscent of Paper Mario 64), Mario gains the power of the stars themselves! Accompanied by Luma, (from luminescent) he can Spin Jump, Ground Pound, Homing Ground Pound, Jump, and use power-ups.
Overall, it's a very good game for both hardcore gamers and casual gamers as hardcore players can unlock a special character after defeating Bowser twice and collecting all 120 stars; while casual gamers can simply defeat Bowser once after collecting 60 stars.
Game On!