There's no telling if there will be a GOTY edition, nor whether it will include pre-order bonuses.
Borderlands 2 just came out, and although I didn't pre-order it I think the bonus(es) they offered were done perfectly. There was, IIRC, an in-game crate containing unique and scaled weapons that give a small edge to the player at whatever level they choose to open it, but doesn't last more than 3-4 levels on average. This could never be unbalancing as the entire game is about constantly finding new and better loot, meaning their shelf life was limited.
Further, they offer the download of an entirely new, fifth class WHEN it's been developed. Meaning that it was NOT developed alongside the main game (beyond I would expect some basic groundwork) so all developer efforts went into the game (*cough* Javik), and not chipping chunks off to re-sell separately.
Not Day 1 DLC, not different for everyone, not withheld from players who didn't pre-order (who can buy it separately), but simply something extra given freely as a reward to thank those that pre-ordered.
I really want Dishonored, but I hate this bonus scheme they've employed. I wouldn't mind if it was an out-of-game item, like a different T-Shirt, character bust or model, etc. but the in-game differences bug me.