I have a PS3, Xbox and a Wii. I play the Wii about 5% and the PS3 95%. The Xbox is my daughters and she plays that almost exclusively, but will play the Wii and PS3 on occasion. I liked the Wii when I first got it, but I grew tired of the novelty rather quickly. I find it too hard to control for games like Call of Duty or Tiger Woods golf. The Wii sports games like tennis, boxing, baseball, etc are fun.
I think if you have had systems like a PS2, Xbox, or Gamecube in the past, and are used to playing games with the more standard controllers, you won’t like playing a lot of the regular games that weren’t specifically designed for the Wii.
Now, as far as would I buy one again, if I had kids in the 6 to 12 year old range, probably. My daughter is 17 and likes some of the games, but plays the Xbox and the PS3 more.
The nice thing about a PS3 is that it plays Blu-ray discs. You can also stream Netflix movies, which you can also do with an Xbox 360, but the Xbox won’t play Blu-ray discs.
Hope that helps.