Recs.
Updated
Specs
Pros
Pro Possibility of advance on royalties to help you complete your game
GOG offers the possibility of an advance on your royalties if you're chosen for their platform. If you take the advance, your revenue split is dropped to 60/40 until the advance is repaid. Could be a good way to get your game across the finish line.
Pro Money back regional pricing
GOG may charge more in some regions as publishers request so. But in those cases they give the extra cash back as credits for buying another game.
For example, the lowest price for the game is U$20 in US, but if in your region it costs U$30 they will give you U$10 back as credits for your next purchase.
Pro Rejected games get a response
GOG.com has a policy of always providing feedback in regards to both your game and its place on the platform. Though it does appear that it is often a form letter with little changed for each developer. So while it may be difficult to know exactly why a game was rejected or if GOG even actually looked at it, there will at least be a confirmation of rejection.
Cons
Con Copy-paste rejection letters
Indie games applying to GOG are reportedly rejected using a copy-paste form letter with a few words changed. The personalised feedback promised to users on the indie game submission page is not provided. In at least one case, it has been claimed that GOG did not look at the game's website or download it before rejecting it.