I had a demo for Mario Party and Sonic and lots more that came with Mario kart double dash for my Gamecube. And I did wanted to buy Mario party. Demos are great
To me, demos are greatly appreciated when it comes to PC gaming, but for somewhat of a different purpose. Sure, I want to see if I'd like the game, but I also want to make sure that my PC can run the game decently.
I sure hope that Batman: Arkham City gets a demo release... Because I may have to upgrade my graphics card for that game...