I think the only time I have ever preordered, I was not disappointed because I got a strategy guide for the game. Still got the BioShock Infinite guide, even though I have never used it.

Otherwise, nowadays, in a basically exclusively digital only world, I could never in good faith preorder a game unless I know I'm getting merch to go with it. I'm talking things like a plushie of the characters or something cool like that. Like how I backed a comic book that is also DLC for a game and am getting a printed copy sent to me for backing enough into it.