Rohan15: I miss demos, helped me decide if I wanted to buy a game or not. After just playing the XCom demo, I am most definitely getting that game. Was fun!
langurmonkey: You have to be careful though unless you have a really powerful PC. Sometimes demos are 100 times more optimized than the full game.
Hmm, could you name some examples?
In my experience, demos are usually much _less_ optimized than the game itself - because the game keeps being patched, whereas the demo usually isn't.
Civ4 had serious compatibility problems with ATI cards, and a totally non-optimized graphics engine (which kept filling the video memory with duplicates of already existing data) on release. The demo still has these problems. The game itself got fixed with a patch. I remember that we kept telling the people who had problems getting the demo to run, that the actual game didn't have these problems anymore, and was in fact quite stable and solid.