Matruchus: Not advocating steam but the game is available drm-free there. You can download it there via client and just move the game folders out and start the game like any other game. Larian stated that the game is released drm-free on Steam.
Niggles: Go buy it then.
Do you really think that GOG has that many die-hard fans to survive long-term future with the day 1 release fails like this?
What I usually see from them is "wishlisted, have a huge backlog, waiting for a sale" or "meh, not a classic", while eager to buy customers have to wait, paying more for releases with missing goodies ("where is the soundtrack?"), big wave of potential linux users was let down from very begining, so they don't even bother to look here anymore, kickstarter backers have never gotten their keys on time etc.,etc...
IMHO GOG is not in that position to afford such a behavior... I can't call it "we are getting games in the best possible form" :(