What is actually the state of SSL on GOG now? I keep myself being bounced between https and http content in a wild fashion on here that seems weirdly inconsistent.
Links on https-secured articles pointing to http game pages, being told that a page can't be loaded because of infinite redirects and cookie oddities... stuff's weird.

So what's the deal? Is GOG fully SSL-enabled? Partially? Not at all supported, but somehow available here and there?

HTTP and HTTPS have been a bit of a mess quite a while now. It was no problem to fully use HTTPS until on a big sale - I think it was the first Insomnia - people were having problems logging in or accessing the checkout page. After that, GOG decided to take load of the HTTPS server to guarantee checking out of the store, because that's what brings money after all. They started to force HTTP on the main site and some weird redirects. It's still possible to to use the site in HTTPS but it's causing trouble occasionally, e.g. with the HTTPSAnywhere plugin, or you have to double log in, or when you log out and reload the page on HTTPS you're still logged in etc.

Long story short, no, GOG is not fully SSL-enabled or at least that's not how gog.com is designed. Though it partially works (actually better than a few weeks ago) and they recently fixed some of the bugs, especially login related.

There's still hope, that with the new account pages currently in development, some of the HTTPS issues get addressed as well.

I can't remember having a single problem since they re-enabled https on www. rather than using a separate domain, so I really don't have any idea what you're talking about.

Maybe it's browser related. Opera (original and Chromium based) doesn't work very well in my experience. It could also be a local issue, as it's quite possible that we're talking about different servers. For example, gog.com was down several times during last Insomnia sale (quite annoying), but apparently mostly for Germans. Meanwhile there seemed to be no problems at all in the US and also other European countries.

No, it's everyone, any browser and everywhere. Randomly. Not all GOG servers are configured the same way, part of the randomness & regional issues. Depends on security add-ons/settings. One normally is transparently redirected from https to http. The problem arises when you try to force the site to stay on https.