Beamer wrote on Jul 6, 2011, 15:15:

The leak isn't a complete build of the game or anything either, far from it.

Oh. That's different.
Leaks in which you can complete, even if buggy, typically damage sales. Yes, it raises pre-release hype, but much of that hype goes into the leaked version and not a paid version.

Let's be honest here - if the game is as good as all the people playing the leak say then it would have received the same positive word of mouth the week of launch that it did the week of leak.