I've seen the Dark Edition at a local store, extremelly expensive since I live outside the US, and it comes with a Quest book and a Slip case just as advertised in Amazon.
The copy I bought at amazon DOES NOT come with the aforementioned bonuses. I receivend only the game case, perfectly sealed but with no quest book nor slip case and it DOES say "Dark Edition".
I can't assure this is the case with the item at the moment but at least the one I bought was incomplete. Sadly, returning it is not an option since sending items to the US is always expensive but I hope this topic helps buyers to be aware of a possible issue.