Reviews are often kind of tricky and there is general skepticism that holds back their controlling potential unless several reviews tend to hold similar opinions. Demos are tricky as well cause sometimes the demo in question is an obvious beta and may not truly reflect the end product while other times it really is just letting you play the first hour of the actual game for free.

So how much sway do they have over you? Name a game where the reviews and/or demos made an impact on purchasing/avoiding it.