Wow, looks like the Xbox1 version is no longer available?? Maybe its just a weird glitch or something. I can only get the PS4 and PC version from there now
EDIT: All 3 are available now on GS. Pre-order bonus appears to be a poster and an "exclusive keychain"
I'm also hoping it'll show up on Amazon soon. Looks like the CE pre-orders are turned off on the official buywitcher site too