Definitely the overall reduction in quality control is the worst bonus of pre-orders.

I think anything game-related is the worst; the game should be made and sold.

An example of a great preorder bonus, I think, was Dante's Inferno: you got a smurfing 8 inch figurine! That's cool as hell!

I would love to see more little mementos like that. The game will eventually sit on a shelf never to be played again, but it's cool to have a figurine, or a medallion, or a nice notepad, or some stuff like that.