I bought Gothic 4 after trying the Steam demo.
I disagree with the bugginess argument, however, unless you are talking about bugs that are so extreme that you actually cannot play the game. Otherwise, why should games be held to a higher standard than any other sort of software application, which regularly ship with lots of bugs?
Unless you are playing pac-man, you will never get to zero bugs because fixing some bugs often results in new bugs or glitches, and this is directly proportional to the complexity of the game.