What's the difference between a Nintendo Wii and other video game consoles?

I.e., what's so good about a Wii? What's all the fuss about?

My daughter has a Wii and it is an amazing console. You have to interact with it to move forward in the games. You can bowl, play tennis, baseball, etc. If you want to play the game right, you get up and get into a baseball hitting stance and swing when the pitch is made. Its awesome. My daughter has most of the game systems and by far the Wii is the best. Her and her friends have a ball playing it. Her dad and I have even bowled and played baseball and tennis.