The best game on the Wii, highly addictive.

Super Mario Galaxy is a top notch game in every aspect. It is probably one of the best games I have ever played.
The graphics are amazing. The lighting is just right, and the cutscenes look like they're from a Pixar movie. The motion is smooth and there are no ugly textures. Space seems to go on forever.
The music is beautiful. Different orchestra music fills every galaxy. Some are calm and relaxing, while others are epic and adventurous. There are also some old tunes for some added nostalgia.
Gameplay is diverse and fun. You can never get bored. The game never feels repetitive. While in most levels you are doing classic SM64 3D running and fighting, there are some very unique ways to complete some galaxies. In some you might be surfing on a stingray on a twisted track. In another, you could be using your pointer to blow a bubble with Mario in it around. In another, you could be tilting your remote to roll around a ball. And on some rare occasions, there are some 2D portions of levels that really add to the nostalgia.
Sound is used at just the right amount. They never get annoying. And instead of talking, Bowser snarls and subtitles are used to translate. If you've played Super Mario Sunshine, you know how annoying Bowser's voice can get.
Controls are crisp and responsive. There is just the right mix of button and motion controls.
Each galaxy is different. No two galaxies are the same. The transformations are cool, too. Mario can turn into a bee, a spring, and even a boo! The galaxies are fun to replay, and you'll never get bored.
The difficulty is just right. While beating the game is easy (You only need half the Power Stars), getting all Stars is a challenge. And the comets add diversity to gameplay.
In conclusion, Super Mario Galaxy isn't cashing in on past success. It's a fresh, new game, and so much fun to play. You'll never feel like you're playing SM64.